Programs & Examples On #Createwindow

Error LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

If it is a windows system, then it may be because you are using 32 bit winpcap library in a 64 bit pc or vie versa. If it is a 64 bit pc then copy the winpcap library and header packet.lib and wpcap.lib from winpcap/lib/x64 to the winpcap/lib directory and overwrite the existing

Drawing Circle with OpenGL

There is another way to draw a circle - draw it in fragment shader. Create a quad:

float right = 0.5;
float bottom = -0.5;
float left = -0.5;
float top = 0.5;
float quad[20] = {
    //x, y, z, lx, ly
    right, bottom, 0, 1.0, -1.0,
    right, top, 0, 1.0, 1.0,
    left, top, 0, -1.0, 1.0,
    left, bottom, 0, -1.0, -1.0,
};

Bind VBO:

unsigned int glBuffer;
glGenBuffers(1, &glBuffer);
glBindBuffer(GL_ARRAY_BUFFER, glBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(float)*20, quad, GL_STATIC_DRAW);

and draw:

#define BUFFER_OFFSET(i) ((char *)NULL + (i))
glEnableVertexAttribArray(ATTRIB_VERTEX);
glEnableVertexAttribArray(ATTRIB_VALUE);
glVertexAttribPointer(ATTRIB_VERTEX , 3, GL_FLOAT, GL_FALSE, 20, 0);
glVertexAttribPointer(ATTRIB_VALUE , 2, GL_FLOAT, GL_FALSE, 20, BUFFER_OFFSET(12));
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

Vertex shader

attribute vec2 value;
uniform mat4 viewMatrix;
uniform mat4 projectionMatrix;
varying vec2 val;
void main() {
    val = value;
    gl_Position = projectionMatrix*viewMatrix*vertex;
}

Fragment shader

varying vec2 val;
void main() {
    float R = 1.0;
    float R2 = 0.5;
    float dist = sqrt(dot(val,val));
    if (dist >= R || dist <= R2) {
        discard;
    }
    float sm = smoothstep(R,R-0.01,dist);
    float sm2 = smoothstep(R2,R2+0.01,dist);
    float alpha = sm*sm2;
    gl_FragColor = vec4(0.0, 0.0, 1.0, alpha);
}

Don't forget to enable alpha blending:

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);

UPDATE: Read more

Creating a 3D sphere in Opengl using Visual C++

I like the answer of coin. It's simple to understand and works with triangles. However the indexes of his program are sometimes over the bounds. So I post here his code with two tiny corrections:

inline void push_indices(vector<GLushort>& indices, int sectors, int r, int s) {
    int curRow = r * sectors;
    int nextRow = (r+1) * sectors;
    int nextS = (s+1) % sectors;

    indices.push_back(curRow + s);
    indices.push_back(nextRow + s);
    indices.push_back(nextRow + nextS);

    indices.push_back(curRow + s);
    indices.push_back(nextRow + nextS);
    indices.push_back(curRow + nextS);
}

void createSphere(vector<vec3>& vertices, vector<GLushort>& indices, vector<vec2>& texcoords,
                  float radius, unsigned int rings, unsigned int sectors)
{
    float const R = 1./(float)(rings-1);
    float const S = 1./(float)(sectors-1);

    for(int r = 0; r < rings; ++r) {
        for(int s = 0; s < sectors; ++s) {
            float const y = sin( -M_PI_2 + M_PI * r * R );
            float const x = cos(2*M_PI * s * S) * sin( M_PI * r * R );
            float const z = sin(2*M_PI * s * S) * sin( M_PI * r * R );

            texcoords.push_back(vec2(s*S, r*R));
            vertices.push_back(vec3(x,y,z) * radius);
            if(r < rings-1)
                push_indices(indices, sectors, r, s);
        }
    }
}

Accessing the last entry in a Map

Find missing all elements from array
        int[] array = {3,5,7,8,2,1,32,5,7,9,30,5};
        TreeMap<Integer, Integer> map = new TreeMap<>();
        for(int i=0;i<array.length;i++) {
            map.put(array[i], 1);
        }
        int maxSize = map.lastKey();
        for(int j=0;j<maxSize;j++) {
            if(null == map.get(j))
                System.out.println("Missing `enter code here`No:"+j);
        }

Excel - extracting data based on another list

I have been hasseling with that as other folks have.

I used the criteria;

=countif(matchingList,C2)=0

where matchingList is the list that i am using as a filter.

have a look at this

http://www.youtube.com/watch?v=x47VFMhRLnM&list=PL63A7644FE57C97F4&index=30

The trick i found is that normally you would have the column heading in the criteria matching the data column heading. this will not work for criteria that is a formula.

What I found was if I left the column heading blank for only the criteria that has the countif formula in the advanced filter works. If I have the column heading i.e. the column heading for column C2 in my formula example then the filter return no output.

Hope this helps

Static linking vs dynamic linking

  • Dynamic linking can reduce total resource consumption (if more than one process shares the same library (including the version in "the same", of course)). I believe this is the argument that drives it its presence in most environments. Here "resources" includes disk space, RAM, and cache space. Of course, if your dynamic linker is insufficiently flexible there is a risk of DLL hell.
  • Dynamic linking means that bug fixes and upgrades to libraries propagate to improve your product without requiring you to ship anything.
  • Plugins always call for dynamic linking.
  • Static linking, means that you can know the code will run in very limited environments (early in the boot process, or in rescue mode).
  • Static linking can make binaries easier to distribute to diverse user environments (at the cost of sending a larger and more resource hungry program).
  • Static linking may allow slightly faster startup times, but this depends to some degree on both the size and complexity of your program and on the details of the OS's loading strategy.

Some edits to include the very relevant suggestions in the comments and in other answers. I'd like to note that the way you break on this depends a lot on what environment you plan to run in. Minimal embedded systems may not have enough resources to support dynamic linking. Slightly larger small systems may well support dynamic linking, because their memory is small enough to make the RAM savings from dynamic linking very attractive. Full blown consumer PCs have, as Mark notes, enormous resources, and you can probably let the convenience issues drive your thinking on this matter.


To address the performance and efficiency issues: it depends.

Classically, dynamic libraries require a some kind of glue layer which often means double dispatch or an extra layer of indirection in function addressing and can cost a little speed (but is function calling time actually a big part of your running time???).

However, if you are running multiple processes which all call the same library a lot, you can end up saving cache lines (and thus winning on running performance) when using dynamic linking relative to using static linking. (Unless modern OS's are smart enough to notice identical segments in statically linked binaries. Seems hard, anyone know?)

Another issue: loading time. You pay loading costs at some point. When you pay this cost depends on how the OS works as well as what linking you use. Maybe you'd rather put off paying it until you know you need it.

Note that static-vs-dynamic linking is traditionally not an optimization issue, because they both involve separate compilation down to object files. However, this is not required: a compiler can in principle, "compile" "static libraries" to a digested AST form initially, and "link" them by adding those ASTs to the ones generated for the main code, thus empowering global optimization. None of the systems I use do this, so I can't comment on how well it works.

The way to answer performance questions is always by testing (and use a test environment as much like the deployment environment as possible).

100% width Twitter Bootstrap 3 template

For Bootstrap 3, you would need to use a custom wrapper and set its width to 100%.

.container-full {
  margin: 0 auto;
  width: 100%;
}

Here is a working example on Bootply

If you prefer not to add a custom class, you can acheive a very wide layout (not 100%) by wrapping everything inside a col-lg-12 (wide layout demo)

Update for Bootstrap 3.1

The container-fluid class has returned in Bootstrap 3.1, so this can be used to create a full width layout (no additional CSS required)..

Bootstrap 3.1 demo

How to unlock android phone through ADB

If you want to open your phone without touching it here is the way

Steps

  1. Make sure you have completed the adb setup in both pc and android
  2. open cmd(Command Prompt)
  3. type adb devices to cheek if your phone is ready or not
  4. If it shows something like
List of devices attached
059c97f4        device

then enter the following command

adb shell input keyevent 26 && adb shell input swipe 600 600 0 0 && adb shell input text <pass> && adb shell input keyevent 66

put your password in <pass> and done. You phone is hopefully opened

Save ArrayList to SharedPreferences

Saving Array in SharedPreferences:

public static boolean saveArray()
{
    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
    SharedPreferences.Editor mEdit1 = sp.edit();
    /* sKey is an array */
    mEdit1.putInt("Status_size", sKey.size());  

    for(int i=0;i<sKey.size();i++)  
    {
        mEdit1.remove("Status_" + i);
        mEdit1.putString("Status_" + i, sKey.get(i));  
    }

    return mEdit1.commit();     
}

Loading Array Data from SharedPreferences

public static void loadArray(Context mContext)
{  
    SharedPreferences mSharedPreference1 =   PreferenceManager.getDefaultSharedPreferences(mContext);
    sKey.clear();
    int size = mSharedPreference1.getInt("Status_size", 0);  

    for(int i=0;i<size;i++) 
    {
     sKey.add(mSharedPreference1.getString("Status_" + i, null));
    }

}

Get URL of ASP.Net Page in code-behind

Do you want the server name? Or the host name?

Request.Url.Host ala Stephen

Dns.GetHostName - Server name

Request.Url will have access to most everything you'll need to know about the page being requested.

Uncaught Invariant Violation: Too many re-renders. React limits the number of renders to prevent an infinite loop

I also have the same problem, and the solution is I didn't bind the event in my onClick. so when it renders for the first time and the data is more, which ends up calling the state setter again, which triggers React to call your function again and so on.

export default function Component(props) {

function clickEvent (event, variable){
    console.log(variable);
}

return (
    <div>
        <IconButton
            key="close"
            aria-label="Close"
            color="inherit"
            onClick={e => clickEvent(e, 10)} // or you can call like this:onClick={() => clickEvent(10)} 
        >
    </div>
)
}

Blank HTML SELECT without blank item in dropdown list

Here is a simple way to do it using plain JavaScript. This is the vanilla equivalent of the jQuery script posted by pimvdb. You can test it here.

<script type='text/javascript'>
  window.onload = function(){
    document.getElementById('id_here').selectedIndex = -1;
  }
</script>

.

<select id="id_here">
  <option>aaaa</option>
  <option>bbbb</option>
</select>

Make sure the "id_here" matches in the form and in the JavaScript.

Find and replace with a newline in Visual Studio Code

  • Control F for search, or Control Shift F for global search
  • Replace >< by >\n< with Regular Expressions enabled

enter image description here

What is the behavior difference between return-path, reply-to and from?

Another way to think about Return-Path vs Reply-To is to compare it to snail mail.

When you send an envelope in the mail, you specify a return address. If the recipient does not exist or refuses your mail, the postmaster returns the envelope back to the return address. For email, the return address is the Return-Path.

Inside of the envelope might be a letter and inside of the letter it may direct the recipient to "Send correspondence to example address". For email, the example address is the Reply-To.

In essence, a Postage Return Address is comparable to SMTP's Return-Path header and SMTP's Reply-To header is similar to the replying instructions contained in a letter.

Ternary operator in AngularJS templates

There it is : ternary operator got added to angular parser in 1.1.5! see the changelog

Here is a fiddle showing new ternary operator used in ng-class directive.

ng-class="boolForTernary ? 'blue' : 'red'"

How to get week numbers from dates?

if you try with lubridate:

library(lubridate)
lubridate::week(ymd("2014-03-16", "2014-03-17","2014-03-18", '2014-01-01'))

[1] 11 11 12  1

The pattern is the same. Try isoweek

lubridate::isoweek(ymd("2014-03-16", "2014-03-17","2014-03-18", '2014-01-01'))
[1] 11 12 12  1

How to fix symbol lookup error: undefined symbol errors in a cluster environment

yum update

helped me out. After I had

wget: symbol lookup error: wget: undefined symbol: psl_latest

test if event handler is bound to an element in jQuery

I wrote a very tiny plugin called "once" which do that:

$.fn.once = function(a, b) {
    return this.each(function() {
        $(this).off(a).on(a,b);
    });
};

And simply:

$(element).once('click', function(){
});

Send HTML in email via PHP

Simplest way is probably to just use Zend Framework or any of the other frameworks like CakePHP or Symphony.

You can do it with the standard mail function too, but you'll need a bit more knowledge on how to attach pictures.

Alternatively, just host the images on a server instead of attaching them. Sending HTML mail is documented in the mail function documentation.

TypeScript: Interfaces vs Types

Examples with Types:

// create a tree structure for an object. You can't do the same with interface because of lack of intersection (&)

type Tree<T> = T & { parent: Tree<T> };

// type to restrict a variable to assign only a few values. Interfaces don't have union (|)

type Choise = "A" | "B" | "C";

// thanks to types, you can declare NonNullable type thanks to a conditional mechanism.

type NonNullable<T> = T extends null | undefined ? never : T;

Examples with Interface:

// you can use interface for OOP and use 'implements' to define object/class skeleton

interface IUser {
    user: string;
    password: string;
    login: (user: string, password: string) => boolean;
}

class User implements IUser {
    user = "user1"
    password = "password1"

    login(user: string, password: string) {
        return (user == user && password == password)
    }
}

// you can extend interfaces with other interfaces

    interface IMyObject {
        label: string,
    }

    interface IMyObjectWithSize extends IMyObject{
        size?: number
    }

Excel VBA: Copying multiple sheets into new workbook

Try do something like this (the problem was that you trying to use MyBook.Worksheets, but MyBook is not a Workbook object, but string, containing workbook name. I've added new varible Set WB = ActiveWorkbook, so you can use WB.Worksheets instead MyBook.Worksheets):

Sub NewWBandPasteSpecialALLSheets()
   MyBook = ActiveWorkbook.Name ' Get name of this book
   Workbooks.Add ' Open a new workbook
   NewBook = ActiveWorkbook.Name ' Save name of new book

   Workbooks(MyBook).Activate ' Back to original book

   Set WB = ActiveWorkbook

   Dim SH As Worksheet

   For Each SH In WB.Worksheets

       SH.Range("WholePrintArea").Copy

       Workbooks(NewBook).Activate

       With SH.Range("A1")
        .PasteSpecial (xlPasteColumnWidths)
        .PasteSpecial (xlFormats)
        .PasteSpecial (xlValues)

       End With

     Next

End Sub

But your code doesn't do what you want: it doesen't copy something to a new WB. So, the code below do it for you:

Sub NewWBandPasteSpecialALLSheets()
   Dim wb As Workbook
   Dim wbNew As Workbook
   Dim sh As Worksheet
   Dim shNew As Worksheet

   Set wb = ThisWorkbook
   Workbooks.Add ' Open a new workbook
   Set wbNew = ActiveWorkbook

   On Error Resume Next

   For Each sh In wb.Worksheets
      sh.Range("WholePrintArea").Copy

      'add new sheet into new workbook with the same name
      With wbNew.Worksheets

          Set shNew = Nothing
          Set shNew = .Item(sh.Name)

          If shNew Is Nothing Then
              .Add After:=.Item(.Count)
              .Item(.Count).Name = sh.Name
              Set shNew = .Item(.Count)
          End If
      End With

      With shNew.Range("A1")
          .PasteSpecial (xlPasteColumnWidths)
          .PasteSpecial (xlFormats)
          .PasteSpecial (xlValues)
      End With
   Next
End Sub

Retrieving a property of a JSON object by index?

My solution:

Object.prototype.__index=function(index)
                         {var i=-1;
                          for (var key in this)
                              {if (this.hasOwnProperty(key) && typeof(this[key])!=='function')
                                  {++i;
                                  }
                               if (i>=index)
                                  {return this[key];
                                  }
                              }
                          return null;
                         }
aObj={'jack':3, 'peter':4, '5':'col', 'kk':function(){alert('hell');}, 'till':'ding'};
alert(aObj.__index(4));

How to hide a navigation bar from first ViewController in Swift?

Ways to show Navigation Bar in Swift:

self.navigationController?.setNavigationBarHidden(false, animated: true)
self.navigationController?.navigationBar.isHidden = false
self.navigationController?.isNavigationBarHidden = false

List file using ls command in Linux with full path

Print the full path (also called resolved path) with:

realpath README.md

In interactive mode you can use shell expansion to list all files in the directory with their full paths:

realpath *

If you're programming a bash script, I guess you'll have a variable for the individual file names.

Thanks to VIPIN KUMAR for pointing to the related readlink command.

Making PHP var_dump() values display one line per value

Yes, try wrapping it with <pre>, e.g.:

echo '<pre>' , var_dump($variable) , '</pre>';

Convert SVG image to PNG with PHP

$command = 'convert -density 300 ';
                        if(Input::Post('height')!='' && Input::Post('width')!=''){
                            $command.='-resize '.Input::Post('width').'x'.Input::Post('height').' ';
                        }
                        $command.=$svg.' '.$source;
                        exec($command);
                        @unlink($svg);

or using : potrace demo :Tool4dev.com

How to access POST form fields

Note for Express 4 users:

If you try and put app.use(express.bodyParser()); into your app, you'll get the following error when you try to start your Express server:

Error: Most middleware (like bodyParser) is no longer bundled with Express and must be installed separately. Please see https://github.com/senchalabs/connect#middleware.

You'll have to install the package body-parser separately from npm, then use something like the following (example taken from the GitHub page):

var express    = require('express');
var bodyParser = require('body-parser');

var app = express();

app.use(bodyParser());

app.use(function (req, res, next) {
  console.log(req.body) // populated!
  next();
})

Get max and min value from array in JavaScript

Instead of .each, another (perhaps more concise) approach to getting all those prices might be:

var prices = $(products).children("li").map(function() {
    return $(this).prop("data-price");
}).get();

additionally you may want to consider filtering the array to get rid of empty or non-numeric array values in case they should exist:

prices = prices.filter(function(n){ return(!isNaN(parseFloat(n))) });

then use Sergey's solution above:

var max = Math.max.apply(Math,prices);
var min = Math.min.apply(Math,prices);

Java 8: How do I work with exception throwing methods in streams?

This question may be a little old, but because I think the "right" answer here is only one way which can lead to some issues hidden Issues later in your code. Even if there is a little Controversy, Checked Exceptions exist for a reason.

The most elegant way in my opinion can you find was given by Misha here Aggregate runtime exceptions in Java 8 streams by just performing the actions in "futures". So you can run all the working parts and collect not working Exceptions as a single one. Otherwise you could collect them all in a List and process them later.

A similar approach comes from Benji Weber. He suggests to create an own type to collect working and not working parts.

Depending on what you really want to achieve a simple mapping between the input values and Output Values occurred Exceptions may also work for you.

If you don't like any of these ways consider using (depending on the Original Exception) at least an own exception.

static and extern global variables in C and C++

Global variables are not extern nor static by default on C and C++. When you declare a variable as static, you are restricting it to the current source file. If you declare it as extern, you are saying that the variable exists, but are defined somewhere else, and if you don't have it defined elsewhere (without the extern keyword) you will get a link error (symbol not found).

Your code will break when you have more source files including that header, on link time you will have multiple references to varGlobal. If you declare it as static, then it will work with multiple sources (I mean, it will compile and link), but each source will have its own varGlobal.

What you can do in C++, that you can't in C, is to declare the variable as const on the header, like this:

const int varGlobal = 7;

And include in multiple sources, without breaking things at link time. The idea is to replace the old C style #define for constants.

If you need a global variable visible on multiple sources and not const, declare it as extern on the header, and then define it, this time without the extern keyword, on a source file:

Header included by multiple files:

extern int varGlobal;

In one of your source files:

int varGlobal = 7;

Docker container will automatically stop after "docker run -d"

Background

A Docker container runs a process (the "command" or "entrypoint") that keeps it alive. The container will continue to run as long as the command continues to run.

In your case, the command (/bin/bash, by default, on centos:latest) is exiting immediately (as bash does when it's not connected to a terminal and has nothing to run).

Normally, when you run a container in daemon mode (with -d), the container is running some sort of daemon process (like httpd). In this case, as long as the httpd daemon is running, the container will remain alive.

What you appear to be trying to do is to keep the container alive without a daemon process running inside the container. This is somewhat strange (because the container isn't doing anything useful until you interact with it, perhaps with docker exec), but there are certain cases where it might make sense to do something like this.

(Did you mean to get to a bash prompt inside the container? That's easy! docker run -it centos:latest)

Solution

A simple way to keep a container alive in daemon mode indefinitely is to run sleep infinity as the container's command. This does not rely doing strange things like allocating a TTY in daemon mode. Although it does rely on doing strange things like using sleep as your primary command.

$ docker run -d centos:latest sleep infinity
$ docker ps
CONTAINER ID  IMAGE         COMMAND          CREATED       STATUS       PORTS NAMES
d651c7a9e0ad  centos:latest "sleep infinity" 2 seconds ago Up 2 seconds       nervous_visvesvaraya

Alternative Solution

As indicated by cjsimon, the -t option allocates a "pseudo-tty". This tricks bash into continuing to run indefinitely because it thinks it is connected to an interactive TTY (even though you have no way to interact with that particular TTY if you don't pass -i). Anyway, this should do the trick too:

$ docker run -t -d centos:latest

Not 100% sure whether -t will produce other weird interactions; maybe leave a comment below if it does.

Reading a JSP variable from JavaScript

alert("${variable}");

or

alert("<%=var%>");

or full example

<html> 
<head>
<script language="javascript"> 

function access(){ 
  <% String str="Hello World"; %>
   var s="<%=str%>"; 
   alert(s); 
} 

</script> 
</head> 

<body onload="access()"> 
</body> 

</html>

Note: sanitize the input before rendering it, it may open whole lot of XSS possibilities

Python Pandas - Missing required dependencies ['numpy'] 1

build_exe_options = {"packages": ["os",'pandas','numpy']}

It works.

Angular: Cannot find a differ supporting object '[object Object]'

If this is an Observable being return in the HTML simply add the async pipe

    observable | async

SQL Server 2008 - Login failed. The login is from an untrusted domain and cannot be used with Windows authentication

You're not passing any credentials to sqlcmd.exe

So it's trying to authenticate you using the Windows Login credentials, but you mustn't have your SQL Server setup to accept those credentials...

When you were installing it, you would have had to supply a Server Admin password (for the sa account)

Try...

sqlcmd.exe -U sa -P YOUR_PASSWORD -S ".\SQL2008"

for reference, theres more details here...

How to extract numbers from a string and get an array of ints?

The accepted answer detects digits but does not detect formated numbers, e.g. 2,000, nor decimals, e.g. 4.8. For such use -?\\d+(,\\d+)*?\\.?\\d+?:

Pattern p = Pattern.compile("-?\\d+(,\\d+)*?\\.?\\d+?");
List<String> numbers = new ArrayList<String>();
Matcher m = p.matcher("Government has distributed 4.8 million textbooks to 2,000 schools");
while (m.find()) {  
    numbers.add(m.group());
}   
System.out.println(numbers);

Output: [4.8, 2,000]

Android Studio Google JAR file causing GC overhead limit exceeded error

4g is a bit overkill, if you do not want to change buildGradle you can use FILE -> Invalid caches / restart.

Thats work fine for me ...

Right mime type for SVG images with fonts embedded

There's only one registered mediatype for SVG, and that's the one you listed, image/svg+xml. You can of course serve SVG as XML too, though browsers tend to behave differently in some scenarios if you do, for example I've seen cases where SVG used in CSS backgrounds fail to display unless served with the image/svg+xml mediatype.

Write to .txt file?

FILE *fp;
char* str = "string";
int x = 10;

fp=fopen("test.txt", "w");
if(fp == NULL)
    exit(-1);
fprintf(fp, "This is a string which is written to a file\n");
fprintf(fp, "The string has %d words and keyword %s\n", x, str);
fclose(fp);

Convert float to string with precision & number of decimal digits specified?

Another option is snprintf:

double pi = 3.1415926;

std::string s(16, '\0');
auto written = std::snprintf(&s[0], s.size(), "%.2f", pi);
s.resize(written);

Demo. Error handling should be added, i.e. checking for written < 0.

Hide password with "•••••••" in a textField

Programmatically (Swift 4 & 5)

self.passwordTextField.isSecureTextEntry = true

no operator "<<" matches these operands

It looks like you're comparing strings incorrectly. To compare a string to another, use the std::string::compare function.

Example

     while ((wrong < MAX_WRONG) && (soFar.compare(THE_WORD) != 0)) 

python date of the previous month

You should use dateutil. With that, you can use relativedelta, it's an improved version of timedelta.

>>> import datetime 
>>> import dateutil.relativedelta
>>> now = datetime.datetime.now()
>>> print now
2012-03-15 12:33:04.281248
>>> print now + dateutil.relativedelta.relativedelta(months=-1)
2012-02-15 12:33:04.281248

How to remove the first Item from a list?

You can find a short collection of useful list functions here.

list.pop(index)

>>> l = ['a', 'b', 'c', 'd']
>>> l.pop(0)
'a'
>>> l
['b', 'c', 'd']
>>> 

del list[index]

>>> l = ['a', 'b', 'c', 'd']
>>> del l[0]
>>> l
['b', 'c', 'd']
>>> 

These both modify your original list.

Others have suggested using slicing:

  • Copies the list
  • Can return a subset

Also, if you are performing many pop(0), you should look at collections.deque

from collections import deque
>>> l = deque(['a', 'b', 'c', 'd'])
>>> l.popleft()
'a'
>>> l
deque(['b', 'c', 'd'])
  • Provides higher performance popping from left end of the list

Change first commit of project with Git?

git rebase -i allows you to conveniently edit any previous commits, except for the root commit. The following commands show you how to do this manually.

# tag the old root, "git rev-list ..." will return the hash of first commit
git tag root `git rev-list HEAD | tail -1`

# switch to a new branch pointing at the first commit
git checkout -b new-root root

# make any edits and then commit them with:
git commit --amend

# check out the previous branch (i.e. master)
git checkout @{-1}

# replace old root with amended version
git rebase --onto new-root root

# you might encounter merge conflicts, fix any conflicts and continue with:
# git rebase --continue

# delete the branch "new-root"
git branch -d new-root

# delete the tag "root"
git tag -d root

How to select the first row of each group?

A nice way of doing this with the dataframe api is using the argmax logic like so

  val df = Seq(
    (0,"cat26",30.9), (0,"cat13",22.1), (0,"cat95",19.6), (0,"cat105",1.3),
    (1,"cat67",28.5), (1,"cat4",26.8), (1,"cat13",12.6), (1,"cat23",5.3),
    (2,"cat56",39.6), (2,"cat40",29.7), (2,"cat187",27.9), (2,"cat68",9.8),
    (3,"cat8",35.6)).toDF("Hour", "Category", "TotalValue")

  df.groupBy($"Hour")
    .agg(max(struct($"TotalValue", $"Category")).as("argmax"))
    .select($"Hour", $"argmax.*").show

 +----+----------+--------+
 |Hour|TotalValue|Category|
 +----+----------+--------+
 |   1|      28.5|   cat67|
 |   3|      35.6|    cat8|
 |   2|      39.6|   cat56|
 |   0|      30.9|   cat26|
 +----+----------+--------+

Is there a simple way to delete a list element by value?

Overwrite the list by indexing everything except the elements you wish to remove

>>> s = [5,4,3,2,1]
>>> s[0:2] + s[3:]
[5, 4, 2, 1]

More generally,

>>> s = [5,4,3,2,1]
>>> i = s.index(3)
>>> s[:i] + s[i+1:]
[5, 4, 2, 1]

Use Excel VBA to click on a button in Internet Explorer, when the button has no "name" associated

With the kind help from Tim Williams, I finally figured out the last détails that were missing. Here's the final code below.

Private Sub Open_multiple_sub_pages_from_main_page()


Dim i As Long
Dim IE As Object
Dim Doc As Object
Dim objElement As Object
Dim objCollection As Object
Dim buttonCollection As Object
Dim valeur_heure As Object


' Create InternetExplorer Object
Set IE = CreateObject("InternetExplorer.Application")
' You can uncoment Next line To see form results
IE.Visible = True

' Send the form data To URL As POST binary request
IE.navigate "http://webpage.com/"

' Wait while IE loading...
While IE.Busy
        DoEvents
Wend


Set objCollection = IE.Document.getElementsByTagName("input")

i = 0
While i < objCollection.Length
    If objCollection(i).Name = "txtUserName" Then
        ' Set text for search
        objCollection(i).Value = "1234"
    End If
    If objCollection(i).Name = "txtPwd" Then
        ' Set text for search
        objCollection(i).Value = "password"
    End If

    If objCollection(i).Type = "submit" And objCollection(i).Name = "btnSubmit" Then ' submit button if found and set
        Set objElement = objCollection(i)
    End If
    i = i + 1
Wend
objElement.Click    ' click button to load page

' Wait while IE re-loading...
While IE.Busy
        DoEvents
Wend

' Show IE
IE.Visible = True
Set Doc = IE.Document

Dim links, link

Dim j As Integer                                                                    'variable to count items
j = 0
Set links = IE.Document.getElementById("dgTime").getElementsByTagName("a")
n = links.Length
While j <= n                                    'loop to go thru all "a" item so it loads next page
    links(j).Click
    While IE.Busy
        DoEvents
    Wend
    '-------------Do stuff here:  copy field value and paste in excel sheet.  Will post another question for this------------------------
    IE.Document.getElementById("DetailToolbar1_lnkBtnSave").Click              'save
    Do While IE.Busy
        Application.Wait DateAdd("s", 1, Now)                                   'wait
    Loop
    IE.Document.getElementById("DetailToolbar1_lnkBtnCancel").Click            'close
    Do While IE.Busy
        Application.Wait DateAdd("s", 1, Now)                                   'wait
    Loop
    Set links = IE.Document.getElementById("dgTime").getElementsByTagName("a")
    j = j + 2
Wend    
End Sub

Why is the time complexity of both DFS and BFS O( V + E )

Your sum

v1 + (incident edges) + v2 + (incident edges) + .... + vn + (incident edges)

can be rewritten as

(v1 + v2 + ... + vn) + [(incident_edges v1) + (incident_edges v2) + ... + (incident_edges vn)]

and the first group is O(N) while the other is O(E).

Using quotation marks inside quotation marks

Python accepts both " and ' as quote marks, so you could do this as:

>>> print '"A word that needs quotation marks"'
"A word that needs quotation marks"

Alternatively, just escape the inner "s

>>> print "\"A word that needs quotation marks\""
"A word that needs quotation marks"

What is a practical, real world example of the Linked List?

A linked list can be used to implement a queue. The canonical real life example would be a line for a cashier.

A linked list can also be used to implement a stack. The cononical real ife example would be one of those plate dispensers at a buffet restaurant where pull the top plate off the top of the stack.

PostgreSQL: role is not permitted to log in

CREATE ROLE blog WITH
  LOGIN
  SUPERUSER
  INHERIT
  CREATEDB
  CREATEROLE
  REPLICATION;

COMMENT ON ROLE blog IS 'Test';

How can I trigger the click event of another element in ng-click using angularjs?

I took the answer posted by Osiloke (Which was the easiest and most complete imho) and I added a change event listener. Works great! Thanks Osiloke. See below if you are interested:

HTML:

  <div file-button>
        <button class='btn btn-success btn-large'>Select your awesome file</button>
   </div>

Directive:

app.directive('fileButton', function() {
  return {
    link: function(scope, element, attributes) {

      var el = angular.element(element)
      var button = el.children()[0]

      el.css({
        position: 'relative',
        overflow: 'hidden',
        width: button.offsetWidth,
        height: button.offsetHeight
      })

      var fileInput = angular.element('<input id='+scope.file_button_id+' type="file" multiple />')
      fileInput.css({
        position: 'absolute',
        top: 0,
        left: 0,
        'z-index': '2',
        width: '100%',
        height: '100%',
        opacity: '0',
        cursor: 'pointer'
      })

      el.append(fileInput)
      document.getElementById(scope.file_button_id).addEventListener('change', scope.file_button_open, false); 
    }
  }
});

Controller:

$scope.file_button_id = "wo_files";    
$scope.file_button_open = function() 
{
  alert("Files are ready!");
}

How to trigger the onclick event of a marker on a Google Maps V3?

I've found out the solution! Thanks to Firebug ;)

//"markers" is an array that I declared which contains all the marker of the map
//"i" is the index of the marker in the array that I want to trigger the OnClick event

//V2 version is:
GEvent.trigger(markers[i], 'click');

//V3 version is:
google.maps.event.trigger(markers[i], 'click');

Installing Python 2.7 on Windows 8

System variables usually require a restart to become effective. Does it still not work after a restart?

Open URL in new window with JavaScript

Just use window.open() function? The third parameter lets you specify window size.

Example

var strWindowFeatures = "location=yes,height=570,width=520,scrollbars=yes,status=yes";
var URL = "https://www.linkedin.com/cws/share?mini=true&amp;url=" + location.href;
var win = window.open(URL, "_blank", strWindowFeatures);

How to step through Python code to help debug issues?

Starting in Python 3.7, you can use the breakpoint() built-in function to enter the debugger:

foo()
breakpoint()  # drop into the debugger at this point
bar()

By default, breakpoint() will import pdb and call pdb.set_trace(). However, you can control debugging behavior via sys.breakpointhook() and use of the environment variable PYTHONBREAKPOINT.

See PEP 553 for more information.

static constructors in C++? I need to initialize private static objects

I guess Simple solution to this will be:

    //X.h
    #pragma once
    class X
    {
    public:
            X(void);
            ~X(void);
    private:
            static bool IsInit;
            static bool Init();
    };

    //X.cpp
    #include "X.h"
    #include <iostream>

    X::X(void)
    {
    }


    X::~X(void)
    {
    }

    bool X::IsInit(Init());
    bool X::Init()
    {
            std::cout<< "ddddd";
            return true;
    }

    // main.cpp
    #include "X.h"
    int main ()
    {
            return 0;
    }

Create dataframe from a matrix

I've found the following "cheat" to work very neatly and error-free

> dimnames <- list(time=c(0, 0.5, 1), name=c("C_0", "C_1"))
> mat <- matrix(data, ncol=2, nrow=3, dimnames=dimnames)
> head(mat, 2) #this returns the number of rows indicated in a data frame format
> df <- data.frame(head(mat, 2)) #"data.frame" might not be necessary

Et voila!

Open page in new window without popup blocking

function openLinkNewTab (url){
    $('body').append('<a id="openLinkNewTab" href="' + url + '" target="_blank"><span></span></a>').find('#openLinkNewTab span').click().remove();
}

Remove Last Comma from a string

function removeLastComma(str) {
   return str.replace(/,(\s+)?$/, '');   
}

Get bottom and right position of an element

Instead of

var bottom = $(window).height() - link.height();
bottom = offset.top - bottom;

Why aren't you doing

var bottom = $(window).height() - top - link.height();

Edit: Your mistake is that you're doing

bottom = offset.top - bottom;

instead of

bottom = bottom - offset.top; // or bottom -= offset.top;

Convert HTML5 into standalone Android App

You could use PhoneGap.

http://phonegap.com/

http://docs.phonegap.com/en/2.1.0/guide_getting-started_android_index.md.html#Getting%20Started%20with%20Android

This has the benefit of being a cross-platform solution. Be warned though that you may need to pay subscription fees. The simplest solution is to just embed a WebView as detailed in @Enigma's answer.

What's the best way to add a drop shadow to my UIView

Wasabii's answer in Swift 2.3:

let shadowPath = UIBezierPath(rect: view.bounds)
view.layer.masksToBounds = false
view.layer.shadowColor = UIColor.blackColor().CGColor
view.layer.shadowOffset = CGSize(width: 0, height: 0.5)
view.layer.shadowOpacity = 0.2
view.layer.shadowPath = shadowPath.CGPath

And in Swift 3/4/5:

let shadowPath = UIBezierPath(rect: view.bounds)
view.layer.masksToBounds = false
view.layer.shadowColor = UIColor.black.cgColor
view.layer.shadowOffset = CGSize(width: 0, height: 0.5)
view.layer.shadowOpacity = 0.2
view.layer.shadowPath = shadowPath.cgPath

Put this code in layoutSubviews() if you're using AutoLayout.

In SwiftUI, this is all much easier:

Color.yellow  // or whatever your view
    .shadow(radius: 3)
    .frame(width: 200, height: 100)

How to set corner radius of imageView?

try this

self.mainImageView.layer.cornerRadius = CGRectGetWidth(self.mainImageView.frame)/4.0
self.mainImageView.clipsToBounds = true

Generate Json schema from XML schema (XSD)

Copy your XML schema here & get the JSON schema code to the online tools which are available to generate JSON schema from XML schema.

cmd line rename file with date and time

I took the above but had to add one more piece because it was putting a space after the hour which gave a syntax error with the rename command. I used:

    set HR=%time:~0,2%
    set HR=%Hr: =0% 
    set HR=%HR: =%
    rename c:\ops\logs\copyinvoices.log copyinvoices_results_%date:~10,4%-%date:~4,2%-%date:~7,2%_%HR%%time:~3,2%.log 

This gave me my format I needed: copyinvoices_results_2013-09-13_0845.log

Specify system property to Maven project

properties-maven-plugin plugin may help:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>properties-maven-plugin</artifactId>
    <version>1.0.0</version>
    <executions>
        <execution>
            <goals>
                <goal>set-system-properties</goal>
            </goals>
            <configuration>
                <properties>
                    <property>
                        <name>my.property.name</name>
                        <value>my.property.value</value>
                    </property>
                </properties>
            </configuration>
        </execution>
    </executions>
</plugin>

correct way to use super (argument passing)

As explained in Python's super() considered super, one way is to have class eat the arguments it requires, and pass the rest on. Thus, when the call-chain reaches object, all arguments have been eaten, and object.__init__ will be called without arguments (as it expects). So your code should look like this:

class A(object):
    def __init__(self, *args, **kwargs):
        print "A"
        super(A, self).__init__(*args, **kwargs)

class B(object):
    def __init__(self, *args, **kwargs):
        print "B"
        super(B, self).__init__(*args, **kwargs)

class C(A):
    def __init__(self, arg, *args, **kwargs):
        print "C","arg=",arg
        super(C, self).__init__(*args, **kwargs)

class D(B):
    def __init__(self, arg, *args, **kwargs):
        print "D", "arg=",arg
        super(D, self).__init__(*args, **kwargs)

class E(C,D):
    def __init__(self, arg, *args, **kwargs):
        print "E", "arg=",arg
        super(E, self).__init__(*args, **kwargs)

print "MRO:", [x.__name__ for x in E.__mro__]
E(10, 20, 30)

How do I run a PowerShell script when the computer starts?

Copy ps1 into this folder, and create it if necessary. It will run at every start-up (before user logon occurs).

C:\Windows\System32\GroupPolicy\Machine\Scripts\Startup

Also it can be done through GPEDIT.msc if available on your OS build (lower level OS maybe not).

How to create PDF files in Python

fpdf is python (too). And often used. See PyPI / pip search. But maybe it was renamed from pyfpdf to fpdf. From features: PNG, GIF and JPG support (including transparency and alpha channel)

Python append() vs. + operator on lists, why do these give different results?

The concatenation operator + is a binary infix operator which, when applied to lists, returns a new list containing all the elements of each of its two operands. The list.append() method is a mutator on list which appends its single object argument (in your specific example the list c) to the subject list. In your example this results in c appending a reference to itself (hence the infinite recursion).

An alternative to '+' concatenation

The list.extend() method is also a mutator method which concatenates its sequence argument with the subject list. Specifically, it appends each of the elements of sequence in iteration order.

An aside

Being an operator, + returns the result of the expression as a new value. Being a non-chaining mutator method, list.extend() modifies the subject list in-place and returns nothing.

Arrays

I've added this due to the potential confusion which the Abel's answer above may cause by mixing the discussion of lists, sequences and arrays. Arrays were added to Python after sequences and lists, as a more efficient way of storing arrays of integral data types. Do not confuse arrays with lists. They are not the same.

From the array docs:

Arrays are sequence types and behave very much like lists, except that the type of objects stored in them is constrained. The type is specified at object creation time by using a type code, which is a single character.

How to Specify "Vary: Accept-Encoding" header in .htaccess

if anyone needs this for NGINX configuration file here is the snippet:

location ~* \.(js|css|xml|gz)$ {
    add_header Vary "Accept-Encoding";
    (... other headers or rules ...)
}

How to interpolate variables in strings in JavaScript, without concatenation?

String.prototype.interpole = function () {
    var c=0, txt=this;
    while (txt.search(/{var}/g) > 0){
        txt = txt.replace(/{var}/, arguments[c]);
        c++;
    }
    return txt;
}

Uso:

var hello = "foo";
var my_string = "I pity the {var}".interpole(hello);
//resultado "I pity the foo"

Convert java.util.Date to String

Altenative one-liners in plain-old java:

String.format("The date: %tY-%tm-%td", date, date, date);

String.format("The date: %1$tY-%1$tm-%1$td", date);

String.format("Time with tz: %tY-%<tm-%<td %<tH:%<tM:%<tS.%<tL%<tz", date);

String.format("The date and time in ISO format: %tF %<tT", date);

This uses Formatter and relative indexing instead of SimpleDateFormat which is not thread-safe, btw.

Slightly more repetitive but needs just one statement. This may be handy in some cases.

iPhone app signing: A valid signing identity matching this profile could not be found in your keychain

I had the exact same problem and tried everything. For whatever reason the solution was that all my certificates had migrated to a keychain called "microsoft_intermediate_certificates". As it probably happened during an Xcode upgrade I have absolutely no idea why, but it may help somebody.

I moved all content of the Microsoft keychain to the login keychain and everything went back to normal.

Use grep to report back only line numbers

I recommend the answers with sed and awk for just getting the line number, rather than using grep to get the entire matching line and then removing that from the output with cut or another tool. For completeness, you can also use Perl:

perl -nE '/pattern/ && say $.' filename

or Ruby:

ruby -ne 'puts $. if /pattern/' filename

Using NOT operator in IF conditions

In general, ! is a perfectly good and readable boolean logic operator. No reason not to use it unless you're simplifying by removing double negatives or applying Morgan's law.

!(!A) = A

or

!(!A | !B) = A & B

As a rule of thumb, keep the signature of your boolean return methods mnemonic and in line with convention. The problem with the scenario that @hvgotcodes proposes is that of course a.b and c.d.e are not very friendly examples to begin with. Suppose you have a Flight and a Seat class for a flight booking application. Then the condition for booking a flight could perfectly be something like

if(flight.isActive() && !seat.isTaken())
{
    //book the seat
}

This perfectly readable and understandable code. You could re-define your boolean logic for the Seat class and rephrase the condition to this, though.

if(flight.isActive() && seat.isVacant())
{
    //book the seat
}

Thus removing the ! operator if it really bothers you, but you'll see that it all depends on what your boolean methods mean.

How to remove the border highlight on an input text element

Use this code:

input:focus {
    outline: 0;
}

HTML text-overflow ellipsis detection

Try this JS function, passing the span element as argument:

function isEllipsisActive(e) {
     return (e.offsetWidth < e.scrollWidth);
}

Python error: "IndexError: string index out of range"

It looks like you indented so_far = new too much. Try this:

if guess in word:
    print("\nYes!", guess, "is in the word!")

    # Create a new variable (so_far) to contain the guess
    new = ""
    i = 0
    for i in range(len(word)):
        if guess == word[i]:
            new += guess
        else:
            new += so_far[i]
    so_far = new # unindented this

PHP - Indirect modification of overloaded property

Nice you gave me something to play around with

Run

class Sample extends Creator {

}

$a = new Sample ();
$a->role->rolename = 'test';
echo  $a->role->rolename , PHP_EOL;
$a->role->rolename->am->love->php = 'w00';
echo  $a->role->rolename  , PHP_EOL;
echo  $a->role->rolename->am->love->php   , PHP_EOL;

Output

test
test
w00

Class Used

abstract class Creator {
    public function __get($name) {
        if (! isset ( $this->{$name} )) {
            $this->{$name} = new Value ( $name, null );
        }
        return $this->{$name};
    }

    public function __set($name, $value) {
        $this->{$name} = new Value ( $name, $value );
    }



}

class Value extends Creator {
    private $name;
    private $value;
    function __construct($name, $value) {
        $this->name = $name;
        $this->value = $value;
    }

    function __toString()
    {
        return (string) $this->value ;
    }
}      

Edit : New Array Support as requested

class Sample extends Creator {

}

$a = new Sample ();
$a->role = array (
        "A",
        "B",
        "C" 
);


$a->role[0]->nice = "OK" ;

print ($a->role[0]->nice  . PHP_EOL);

$a->role[1]->nice->ok = array("foo","bar","die");

print ($a->role[1]->nice->ok[2]  . PHP_EOL);


$a->role[2]->nice->raw = new stdClass();
$a->role[2]->nice->raw->name = "baba" ;

print ($a->role[2]->nice->raw->name. PHP_EOL);

Output

 Ok die baba

Modified Class

abstract class Creator {
    public function __get($name) {
        if (! isset ( $this->{$name} )) {
            $this->{$name} = new Value ( $name, null );
        }
        return $this->{$name};
    }

    public function __set($name, $value) {
        if (is_array ( $value )) {
            array_walk ( $value, function (&$item, $key) {
                $item = new Value ( $key, $item );
            } );
        }
        $this->{$name} = $value;

    }

}

class Value {
    private $name ;
    function __construct($name, $value) {
        $this->{$name} = $value;
        $this->name = $value ;
    }

    public function __get($name) {
        if (! isset ( $this->{$name} )) {
            $this->{$name} = new Value ( $name, null );
        }

        if ($name == $this->name) {
            return $this->value;
        }

        return $this->{$name};
    }

    public function __set($name, $value) {
        if (is_array ( $value )) {
            array_walk ( $value, function (&$item, $key) {
                $item = new Value ( $key, $item );
            } );
        }
        $this->{$name} = $value;
    }

    public function __toString() {
        return (string) $this->name ;
    }   
}

Does Notepad++ show all hidden characters?

Yes, and unfortunately you cannot turn them off, or any other special characters. The options under \View\Show Symbols only turns on or off things like tabs, spaces, EOL, etc. So if you want to read some obscure coding with text in it - you actually need to look elsewhere. I also looked at changing the coding, ASCII is not listed, and that would not make the mess invisible anyway.

How to use BeginInvoke C#

Action is a Type of Delegate provided by the .NET framework. The Action points to a method with no parameters and does not return a value.

() => is lambda expression syntax. Lambda expressions are not of Type Delegate. Invoke requires Delegate so Action can be used to wrap the lambda expression and provide the expected Type to Invoke()

Invoke causes said Action to execute on the thread that created the Control's window handle. Changing threads is often necessary to avoid Exceptions. For example, if one tries to set the Rtf property on a RichTextBox when an Invoke is necessary, without first calling Invoke, then a Cross-thread operation not valid exception will be thrown. Check Control.InvokeRequired before calling Invoke.

BeginInvoke is the Asynchronous version of Invoke. Asynchronous means the thread will not block the caller as opposed to a synchronous call which is blocking.

Clear the form field after successful submission of php form

If you want your form's field clear, you must only add a delay in the onClick event like:

<input name="submit" id="MyButton" type="submit" class="btn-lg" value="ClickMe" onClick="setTimeout('clearform()', 2000 );"

onClick="setTimeout('clearform()', 1500 );" . in 1,5 seconds its clear

document.getElementById("name").value = "";  <<<<<<just correct this
document.getElementById("telephone").value = "";    <<<<<correct this

By clearform(), I mean your clearing-fields function.

How to strip HTML tags with jQuery?

Use the .text() function:

var text = $("<p> example ive got a string</P>").text();

Update: As Brilliand points out below, if the input string does not contain any tags and you are unlucky enough, it might be treated as a CSS selector. So this version is more robust:

var text = $("<div/>").html("<p> example ive got a string</P>").text();

String concatenation in Jinja

My bad, in trying to simplify it, I went too far, actually stuffs is a record of all kinds of info, I just want the id in it.

stuffs = [[123, first, last], [456, first, last]]

I want my_sting to be

my_sting = '123, 456'

My original code should have looked like this:

{% set my_string = '' %}
{% for stuff in stuffs %}
{% set my_string = my_string + stuff.id + ', '%}
{% endfor%}

Thinking about it, stuffs is probably a dictionary, but you get the gist.

Yes I found the join filter, and was going to approach it like this:

 {% set my_string = [] %}
 {% for stuff in stuffs %}
 {% do my_string.append(stuff.id) %}
 {% endfor%}
 {%  my_string|join(', ') %}

But the append doesn't work without importing the extensions to do it, and reading that documentation gave me a headache. It doesn't explicitly say where to import it from or even where you would put the import statement, so I figured finding a way to concat would be the lesser of the two evils.

The project type is not supported by this installation

You might need to install the "Microsoft Web Platform Installer" from http://www.microsoft.com/web/downloads/platform.aspx

how to fix EXE4J_JAVA_HOME, No JVM could be found on your system error?

Leave you stuff there and Try the following as well:

Start > Right-click on My computer > Properties > Advanced system settings > Environment Variables > look for variable name called "Path" in the lower box

set path value value as: (you can just add it to the starting of line, don't forgot semi column in between )

c:\Program Files\java\jre7\bin

How do you check current view controller class in Swift?

Swift 3 | Check if a view controller is the root from within itself.

You can access window from within a view controller, you just need to use self.view.window.

Context: I need to update the position of a view and trigger an animation when the device is rotated. I only want to do this if the view controller is active.

class MyViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(
            self, 
            selector: #selector(deviceDidRotate), 
            name: .UIApplicationDidChangeStatusBarOrientation, 
            object: nil
        )
    }

    func deviceDidRotate() {
        guard let window = self.view.window else { return }

        // check if self is root view controller
        if window.rootViewController == self {
            print("vc is self")
        }

        // check if root view controller is instance of MyViewController
        if window.rootViewController is MyViewController {
            print("vc is MyViewController")
        }
    }
}

If you rotate your device while MyViewController is active, you will see the above lines print to the console. If MyViewController is not active, you will not see them.

If you're curious why I'm using UIDeviceOrientationDidChange instead of .UIDeviceOrientationDidChange, look at this answer.

How to Create Multiple Where Clause Query Using Laravel Eloquent?

You can use eloquent in Laravel 5.3

All results

UserModel::where('id_user', $id_user)
                ->where('estado', 1)
                ->get();

Partial results

UserModel::where('id_user', $id_user)
                    ->where('estado', 1)
                    ->pluck('id_rol');

Changing capitalization of filenames in Git

Considering larsks' answer, you can get it working with a single command with "--force":

 git mv --force myfile MyFile

Why do we usually use || over |? What is the difference?

If you use the || and && forms, rather than the | and & forms of these operators, Java will not bother to evaluate the right-hand operand alone.

It's a matter of if you want to short-circuit the evaluation or not -- most of the time you want to.

A good way to illustrate the benefits of short-circuiting would be to consider the following example.

Boolean b = true;
if(b || foo.timeConsumingCall())
{
   //we entered without calling timeConsumingCall()
}

Another benefit, as Jeremy and Peter mentioned, for short-circuiting is the null reference check:

if(string != null && string.isEmpty())
{
    //we check for string being null before calling isEmpty()
}

more info

Access cell value of datatable

string abc= dt.Rows[0]["column name"].ToString();

How to get the current working directory in Java?

this is current directory name

String path="/home/prasad/Desktop/folderName";
File folder = new File(path);
String folderName=folder.getAbsoluteFile().getName();

this is current directory path

String path=folder.getPath();

Return 0 if field is null in MySQL

You can use coalesce(column_name,0) instead of just column_name. The coalesce function returns the first non-NULL value in the list.

I should mention that per-row functions like this are usually problematic for scalability. If you think your database may get to be a decent size, it's often better to use extra columns and triggers to move the cost from the select to the insert/update.

This amortises the cost assuming your database is read more often than written (and most of them are).

Java switch statement: Constant expression required, but it IS constant

If you're using it in a switch case then you need to get the type of the enum even before you plug that value in the switch. For instance :

SomeEnum someEnum = SomeEnum.values()[1];

switch (someEnum) {
            case GRAPES:
            case BANANA: ...

And the enum is like:

public enum SomeEnum {

    GRAPES("Grapes", 0),
    BANANA("Banana", 1),

    private String typeName;
    private int typeId;

    SomeEnum(String typeName, int typeId){
        this.typeName = typeName;
        this.typeId = typeId;
    }
}

ApiNotActivatedMapError for simple html page using google-places-api

as of Jan 2017, unfortunately @Adi's answer, while it seems like it should work, does not. (Google's API key process is buggy)

you'll need to click "get a key" from this link: https://developers.google.com/maps/documentation/javascript/get-api-key

also I strongly recommend you don't ever choose "secure key" until you are ready to switch to production. I did http referrer restrictions on a key and afterwards was unable to get it working with localhost, even after disabling security for the key. I had to create a new key for it to work again.

Enable 'xp_cmdshell' SQL Server

You can also hide again advanced option after reconfigure:

-- show advanced options
EXEC sp_configure 'show advanced options', 1
GO
RECONFIGURE
GO
-- enable xp_cmdshell
EXEC sp_configure 'xp_cmdshell', 1
GO
RECONFIGURE
GO
-- hide advanced options
EXEC sp_configure 'show advanced options', 0
GO
RECONFIGURE
GO

Java Command line arguments

Every Java program starts with

public static void main(String[] args) {

That array of type String that main() takes as a parameter holds the command line arguments to your program. If the user runs your program as

$ java myProgram a

then args[0] will hold the String "a".

What are the calling conventions for UNIX & Linux system calls (and user-space functions) on i386 and x86-64

Linux kernel 5.0 source comments

I knew that x86 specifics are under arch/x86, and that syscall stuff goes under arch/x86/entry. So a quick git grep rdi in that directory leads me to arch/x86/entry/entry_64.S:

/*
 * 64-bit SYSCALL instruction entry. Up to 6 arguments in registers.
 *
 * This is the only entry point used for 64-bit system calls.  The
 * hardware interface is reasonably well designed and the register to
 * argument mapping Linux uses fits well with the registers that are
 * available when SYSCALL is used.
 *
 * SYSCALL instructions can be found inlined in libc implementations as
 * well as some other programs and libraries.  There are also a handful
 * of SYSCALL instructions in the vDSO used, for example, as a
 * clock_gettimeofday fallback.
 *
 * 64-bit SYSCALL saves rip to rcx, clears rflags.RF, then saves rflags to r11,
 * then loads new ss, cs, and rip from previously programmed MSRs.
 * rflags gets masked by a value from another MSR (so CLD and CLAC
 * are not needed). SYSCALL does not save anything on the stack
 * and does not change rsp.
 *
 * Registers on entry:
 * rax  system call number
 * rcx  return address
 * r11  saved rflags (note: r11 is callee-clobbered register in C ABI)
 * rdi  arg0
 * rsi  arg1
 * rdx  arg2
 * r10  arg3 (needs to be moved to rcx to conform to C ABI)
 * r8   arg4
 * r9   arg5
 * (note: r12-r15, rbp, rbx are callee-preserved in C ABI)
 *
 * Only called from user space.
 *
 * When user can change pt_regs->foo always force IRET. That is because
 * it deals with uncanonical addresses better. SYSRET has trouble
 * with them due to bugs in both AMD and Intel CPUs.
 */

and for 32-bit at arch/x86/entry/entry_32.S:

/*
 * 32-bit SYSENTER entry.
 *
 * 32-bit system calls through the vDSO's __kernel_vsyscall enter here
 * if X86_FEATURE_SEP is available.  This is the preferred system call
 * entry on 32-bit systems.
 *
 * The SYSENTER instruction, in principle, should *only* occur in the
 * vDSO.  In practice, a small number of Android devices were shipped
 * with a copy of Bionic that inlined a SYSENTER instruction.  This
 * never happened in any of Google's Bionic versions -- it only happened
 * in a narrow range of Intel-provided versions.
 *
 * SYSENTER loads SS, ESP, CS, and EIP from previously programmed MSRs.
 * IF and VM in RFLAGS are cleared (IOW: interrupts are off).
 * SYSENTER does not save anything on the stack,
 * and does not save old EIP (!!!), ESP, or EFLAGS.
 *
 * To avoid losing track of EFLAGS.VM (and thus potentially corrupting
 * user and/or vm86 state), we explicitly disable the SYSENTER
 * instruction in vm86 mode by reprogramming the MSRs.
 *
 * Arguments:
 * eax  system call number
 * ebx  arg1
 * ecx  arg2
 * edx  arg3
 * esi  arg4
 * edi  arg5
 * ebp  user stack
 * 0(%ebp) arg6
 */

glibc 2.29 Linux x86_64 system call implementation

Now let's cheat by looking at a major libc implementations and see what they are doing.

What could be better than looking into glibc that I'm using right now as I write this answer? :-)

glibc 2.29 defines x86_64 syscalls at sysdeps/unix/sysv/linux/x86_64/sysdep.h and that contains some interesting code, e.g.:

/* The Linux/x86-64 kernel expects the system call parameters in
   registers according to the following table:

    syscall number  rax
    arg 1       rdi
    arg 2       rsi
    arg 3       rdx
    arg 4       r10
    arg 5       r8
    arg 6       r9

    The Linux kernel uses and destroys internally these registers:
    return address from
    syscall     rcx
    eflags from syscall r11

    Normal function call, including calls to the system call stub
    functions in the libc, get the first six parameters passed in
    registers and the seventh parameter and later on the stack.  The
    register use is as follows:

     system call number in the DO_CALL macro
     arg 1      rdi
     arg 2      rsi
     arg 3      rdx
     arg 4      rcx
     arg 5      r8
     arg 6      r9

    We have to take care that the stack is aligned to 16 bytes.  When
    called the stack is not aligned since the return address has just
    been pushed.


    Syscalls of more than 6 arguments are not supported.  */

and:

/* Registers clobbered by syscall.  */
# define REGISTERS_CLOBBERED_BY_SYSCALL "cc", "r11", "cx"

#undef internal_syscall6
#define internal_syscall6(number, err, arg1, arg2, arg3, arg4, arg5, arg6) \
({                                  \
    unsigned long int resultvar;                    \
    TYPEFY (arg6, __arg6) = ARGIFY (arg6);              \
    TYPEFY (arg5, __arg5) = ARGIFY (arg5);              \
    TYPEFY (arg4, __arg4) = ARGIFY (arg4);              \
    TYPEFY (arg3, __arg3) = ARGIFY (arg3);              \
    TYPEFY (arg2, __arg2) = ARGIFY (arg2);              \
    TYPEFY (arg1, __arg1) = ARGIFY (arg1);              \
    register TYPEFY (arg6, _a6) asm ("r9") = __arg6;            \
    register TYPEFY (arg5, _a5) asm ("r8") = __arg5;            \
    register TYPEFY (arg4, _a4) asm ("r10") = __arg4;           \
    register TYPEFY (arg3, _a3) asm ("rdx") = __arg3;           \
    register TYPEFY (arg2, _a2) asm ("rsi") = __arg2;           \
    register TYPEFY (arg1, _a1) asm ("rdi") = __arg1;           \
    asm volatile (                          \
    "syscall\n\t"                           \
    : "=a" (resultvar)                          \
    : "0" (number), "r" (_a1), "r" (_a2), "r" (_a3), "r" (_a4),     \
      "r" (_a5), "r" (_a6)                      \
    : "memory", REGISTERS_CLOBBERED_BY_SYSCALL);            \
    (long int) resultvar;                       \
})

which I feel are pretty self explanatory. Note how this seems to have been designed to exactly match the calling convention of regular System V AMD64 ABI functions: https://en.wikipedia.org/wiki/X86_calling_conventions#List_of_x86_calling_conventions

Quick reminder of the clobbers:

  • cc means flag registers. But Peter Cordes comments that this is unnecessary here.
  • memory means that a pointer may be passed in assembly and used to access memory

For an explicit minimal runnable example from scratch see this answer: How to invoke a system call via syscall or sysenter in inline assembly?

Make some syscalls in assembly manually

Not very scientific, but fun:

  • x86_64.S

    .text
    .global _start
    _start:
    asm_main_after_prologue:
        /* write */
        mov $1, %rax    /* syscall number */
        mov $1, %rdi    /* stdout */
        mov $msg, %rsi  /* buffer */
        mov $len, %rdx  /* len */
        syscall
    
        /* exit */
        mov $60, %rax   /* syscall number */
        mov $0, %rdi    /* exit status */
        syscall
    msg:
        .ascii "hello\n"
    len = . - msg
    

    GitHub upstream.

Make system calls from C

Here's an example with register constraints: How to invoke a system call via syscall or sysenter in inline assembly?

aarch64

I've shown a minimal runnable userland example at: https://reverseengineering.stackexchange.com/questions/16917/arm64-syscalls-table/18834#18834 TODO grep kernel code here, should be easy.

Undefined columns selected when subsetting data frame

You want rows where that condition is true so you need a comma:

data[data$Ozone > 14, ]

Using for loop inside of a JSP

Do this

    <% for(int i = 0; i < allFestivals.size(); i+=1) { %>
        <tr>      
            <td><%=allFestivals.get(i).getFestivalName()%></td>
        </tr>
    <% } %>

Better way is to use c:foreach see link jstl for each

How to set focus to a button widget programmatically?

Yeah it's possible.

Button myBtn = (Button)findViewById(R.id.myButtonId);
myBtn.requestFocus();

or in XML

<Button ...><requestFocus /></Button>

Important Note: The button widget needs to be focusable and focusableInTouchMode. Most widgets are focusable but not focusableInTouchMode by default. So make sure to either set it in code

myBtn.setFocusableInTouchMode(true);

or in XML

android:focusableInTouchMode="true"

How to convert ASCII code (0-255) to its corresponding character?

This is an example, which shows that by converting an int to char, one can determine the corresponding character to an ASCII code.

public class sample6
{
    public static void main(String... asf)
    {

        for(int i =0; i<256; i++)
        {
            System.out.println( i + ". " + (char)i);
        }
    }
}

How to get two or more commands together into a batch file

if I understand you right (not sure), the start parameter /D should help you:

start "cmd" /D %PathName% %comd%

/D sets the start-directory (see start /?)

How do I convert from BLOB to TEXT in MySQL?

SELECCT TO_BASE64(blobfield)  
FROM the Table

worked for me.

The CAST(blobfield AS CHAR(10000) CHARACTER SET utf8) and CAST(blobfield AS CHAR(10000) CHARACTER SET utf16) did not show me the text value I wanted to get.

How to enable php7 module in apache?

For Windows users looking for solution of same problem. I just repleced

LoadModule php7_module "C:/xampp/php/php7apache2_4.dll"

in my /conf/extra/http?-xampp.conf

Ignore invalid self-signed ssl certificate in node.js with https.request?

Add the following environment variable:

NODE_TLS_REJECT_UNAUTHORIZED=0

e.g. with export:

export NODE_TLS_REJECT_UNAUTHORIZED=0

(with great thanks to Juanra)

Disabling right click on images using jquery

For Disable Right Click Option

<script type="text/javascript">
    var message="Function Disabled!";

    function clickIE4(){
        if (event.button==2){
            alert(message);
            return false;
        }
    }

    function clickNS4(e){
        if (document.layers||document.getElementById&&!document.all){
            if (e.which==2||e.which==3){
                alert(message);
                return false;
            }
        }
    }

    if (document.layers){
        document.captureEvents(Event.MOUSEDOWN);
        document.onmousedown=clickNS4;
    }
    else if (document.all&&!document.getElementById){
        document.onmousedown=clickIE4;
    }

    document.oncontextmenu=new Function("alert(message);return false")
</script>

Xcode build failure "Undefined symbols for architecture x86_64"

Undefined symbols for architecture x86_64: "_OBJC_CLASS_$_xxx", referenced from: objc-class-ref in yyy.o

This generally means, you are calling "xxx" (it may be a framework or class) from the class "yyy". The compiler can not locate the "xxx" so this error occurs.

You need to add the missing files(in this case "xxx") by right click on your project folder in navigator window and tap on "Add files to "YourProjectName"" option.

A popup window will open your project files in Finder. There, you can see the missing files and just add them to your project. Don't forget to check the "Copy items if needed" box. Good luck!!

The service cannot be started, either because it is disabled or because it has no enabled devices associated with it

Try to open Services Window, by writing services.msc into Start->Run and hit Enter.

When window appears, then find SQL Browser service, right click and choose Properties, and then in dropdown list choose Automatic, or Manual, whatever you want, and click OK. Eventually, if not started immediately, you can again press right click on this service and click Start.

How to order results with findBy() in Doctrine

$cRepo = $em->getRepository('KaleLocationBundle:Country');

// Leave the first array blank
$countries = $cRepo->findBy(array(), array('name'=>'asc'));

Sort Array of object by object field in Angular 6

Not tested but should work

 products.sort((a,b)=>a.title.rendered > b.title.rendered)

Google MAP API Uncaught TypeError: Cannot read property 'offsetWidth' of null

This problem is usually due to the map div not being rendered before the javascript runs that needs to access it.

You should put your initialization code inside an onload function or at the bottom of your HTML file, just before the tag, so the DOM is completely rendered before it executes (note that the second option is more sensitive to invalid HTML).

Note, as pointed out by matthewsheets this also could be cause by the div with that id not existing at all in your HTML (the pathological case of the div not being rendered)

Adding code sample from wf9a5m75's post to put everything in one place:

<script type="text/javascript">

function initialize() {
    var latlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions = {
        zoom: 8,
        center: latlng,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    };
    var map = new google.maps.Map(document.getElementById("map_canvas"),
            myOptions);
}
google.maps.event.addDomListener(window, "load", initialize);

</script>

iOS 7 - Status bar overlaps the view

If you simply do NOT want any status bar at all, you need to update your plist with this data: To do this, in the plist, add those 2 settings:

<key>UIStatusBarHidden</key>
<true/>
<key>UIViewControllerBasedStatusBarAppearance</key>
<false/>

In iOS 7 you are expected to design your app with an overlaid transparent status bar in mind. See the new iOS 7 Weather app for example.

Android Studio: Add jar as library?

'compile files...' used to work for me, but not any more. after much pain, I found that using this instead works:

compile fileTree(dir: 'libs', include: '*.jar')

I have no idea why that made a difference, but, at least the damn thing is working now.

How to fix the Eclipse executable launcher was unable to locate its companion shared library for windows 7?

In my case, i had copied a plugins folder into workspace from a collegue. Becaouse it was an unzipped folder, the structure was like 'pluginsfolder inside a plugins folder2 . so make sure that all the plugins are directly located under the toppest plugins folder at the workspace.

get UTC timestamp in python with datetime

The accepted answer seems not work for me. My solution:

import time
utc_0 = int(time.mktime(datetime(1970, 01, 01).timetuple()))
def datetime2ts(dt):
    """Converts a datetime object to UTC timestamp"""
    return int(time.mktime(dt.utctimetuple())) - utc_0

Determine path of the executing script

You can wrap the r script in a bash script and retrieve the script's path as a bash variable like so:

#!/bin/bash
     # [environment variables can be set here]
     path_to_script=$(dirname $0)

     R --slave<<EOF
        source("$path_to_script/other.R")

     EOF

Pass C# ASP.NET array to Javascript array

Prepare an array (in my case it is 2d array):

        // prepare a 2d array in c#
        ArrayList header = new ArrayList { "Task Name", "Hours"};
        ArrayList data1 = new ArrayList {"Work", 2};
        ArrayList data2 = new ArrayList { "Eat", 2 };
        ArrayList data3 = new ArrayList { "Sleep", 2 };
        ArrayList data = new ArrayList {header, data1, data2, data3};
        // convert it in json
        string dataStr = JsonConvert.SerializeObject(data, Formatting.None);
        // store it in viewdata/ viewbag
        ViewBag.Data = new HtmlString(dataStr);   

Parse it in the view.

<script>    
    var data = JSON.parse('@ViewBag.Data');
    console.log(data);
</script>

In your case you can directly use variable name instead of ViewBag.Data.

How to use "like" and "not like" in SQL MSAccess for the same field?

What I found out is that MS Access will reject --Not Like "BB*"-- if not enclosed in PARENTHESES, unlike --Like "BB*"-- which is ok without parentheses.

I tested these on MS Access 2010 and are all valid:

  1. Like "BB"

  2. (Like "BB")

  3. (Not Like "BB")

How to work with progress indicator in flutter?

I suggest to use this plugin flutter_easyloading

flutter_easyloading is clean and lightweight Loading widget for Flutter App, easy to use without context, support iOS and Android

Add this to your package's pubspec.yaml file:

dependencies:
  flutter_easyloading: ^2.0.0

Now in your Dart code, you can use:

import 'package:flutter_easyloading/flutter_easyloading.dart';

To use First, initialize FlutterEasyLoading in MaterialApp/CupertinoApp

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter EasyLoading',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter EasyLoading'),
      builder: EasyLoading.init(),
    );
  }
}

EasyLoading is a singleton, so you can custom loading style any where like this:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter_easyloading/flutter_easyloading.dart';
import './custom_animation.dart';

void main() {
  runApp(MyApp());
  configLoading();
}

void configLoading() {
  EasyLoading.instance
    ..displayDuration = const Duration(milliseconds: 2000)
    ..indicatorType = EasyLoadingIndicatorType.fadingCircle
    ..loadingStyle = EasyLoadingStyle.dark
    ..indicatorSize = 45.0
    ..radius = 10.0
    ..progressColor = Colors.yellow
    ..backgroundColor = Colors.green
    ..indicatorColor = Colors.yellow
    ..textColor = Colors.yellow
    ..maskColor = Colors.blue.withOpacity(0.5)
    ..userInteractions = true
    ..customAnimation = CustomAnimation();
}

Then, use per your requirement

import 'package:flutter/material.dart';
import 'package:flutter_easyloading/flutter_easyloading.dart';
import 'package:dio/dio.dart';

class TestPage extends StatefulWidget {
  @override
  _TestPageState createState() => _TestPageState();
}

class _TestPageState extends State<TestPage> {
  @override
  void initState() {
    super.initState();
    // EasyLoading.show();
  }

  @override
  void deactivate() {
    EasyLoading.dismiss();
    super.deactivate();
  }

  void loadData() async {
    try {
      EasyLoading.show();
      Response response = await Dio().get('https://github.com');
      print(response);
      EasyLoading.dismiss();
    } catch (e) {
      EasyLoading.showError(e.toString());
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter EasyLoading'),
      ),
      body: Center(
        child: FlatButton(
          textColor: Colors.blue,
          child: Text('loadData'),
          onPressed: () {
            loadData();
            // await Future.delayed(Duration(seconds: 2));
            // EasyLoading.show(status: 'loading...');
            // await Future.delayed(Duration(seconds: 5));
            // EasyLoading.dismiss();
          },
        ),
      ),
    );
  }
}

enter image description here

How can I resize an image dynamically with CSS as the browser width/height changes?

This can be done with pure CSS and does not even require media queries.

To make the images flexible, simply add max-width:100% and height:auto. Image max-width:100% and height:auto works in IE7, but not in IE8 (yes, another weird IE bug). To fix this, you need to add width:auto\9 for IE8.

source: http://webdesignerwall.com/tutorials/responsive-design-with-css3-media-queries

CSS:

img {
    max-width: 100%;
    height: auto;
    width: auto\9; /* ie8 */
}

And if you want to enforce a fixed max width of the image, just place it inside a container, for example:

<div style="max-width:500px;">
    <img src="..." />
</div>

JSFiddle example here. No JavaScript required. Works in latest versions of Chrome, Firefox and IE (which is all I've tested).

Invisible characters - ASCII

There is actually a truly invisible character: U+FEFF. This character is called the Byte Order Mark and is related to the Unicode 8 system. It is a really confusing concept that can be explained HERE The Byte Order Mark or BOM for short is an invisible character that doesn't take up any space. You can copy the character bellow between the > and <.

Here is the character:

> <

How to catch this character in action:

  • Copy the character between the > and <,
  • Write a line of text, then randomly put your caret in the line of text
  • Paste the character in the line.
  • Go to the beginning of the line and press and hold the right arrow key.

You will notice that when your caret gets to the place you pasted the character, it will briefly stop for around half a second. This is becuase the caret is passing over the invisible character. Even though you can't see it doesn't mean it isn't there. The caret still sees that there is a character in that area that you pasted the BOM and will pass through it. Since the BOM is invisble, the caret will look like it has paused for a brief moment. You can past the BOM multiple times in an area and redo the steps above to really show the affect. Good luck!

EDIT: Sadly, Stackoverflow doesn't like the character. Here is an example from w3.org: https://www.w3.org/International/questions/examples/phpbomtest.php

SCP Permission denied (publickey). on EC2 only when using -r flag on directories

I was initially running:

sudo scp

Once I ran just scp, without sudo, it copied everything fine:

scp

It seems to me that sudo scp command wasn't reading my current user's SSH public key at ~/.ssh/id_rsa.pub.

scipy.misc module has no attribute imread?

The only way I could get the .png file I'm working with in as uint8 was with OpenCv.

cv2.imread(file) actually returned numpy.ndarray with dtype=uint8

How to check if a column exists in Pandas

Just to suggest another way without using if statements, you can use the get() method for DataFrames. For performing the sum based on the question:

df['sum'] = df.get('A', df['B']) + df['C']

The DataFrame get method has similar behavior as python dictionaries.

How do you make a deep copy of an object?

You can make a deep copy with serialization without creating files.

Your object you wish to deep copy will need to implement serializable. If the class isn't final or can't be modified, extend the class and implement serializable.

Convert your class to a stream of bytes:

ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(object);
oos.flush();
oos.close();
bos.close();
byte[] byteData = bos.toByteArray();

Restore your class from a stream of bytes:

ByteArrayInputStream bais = new ByteArrayInputStream(byteData);
(Object) object = (Object) new ObjectInputStream(bais).readObject();

Python int to binary string?

A simple way to do that is to use string format, see this page.

>> "{0:b}".format(10)
'1010'

And if you want to have a fixed length of the binary string, you can use this:

>> "{0:{fill}8b}".format(10, fill='0')
'00001010'

If two's complement is required, then the following line can be used:

'{0:{fill}{width}b}'.format((x + 2**n) % 2**n, fill='0', width=n)

where n is the width of the binary string.

What is the App_Data folder used for in Visual Studio?

It's a place to put an embedded database, such as Sql Server Express, Access, or SQLite.

JSON - Iterate through JSONArray

You could try my (*heavily borrowed from various sites) recursive method to go through all JSON objects and JSON arrays until you find JSON elements. This example actually searches for a particular key and returns all values for all instances of that key. 'searchKey' is the key you are looking for.

ArrayList<String> myList = new ArrayList<String>();
myList = findMyKeyValue(yourJsonPayload,null,"A"); //if you only wanted to search for A's values

    private ArrayList<String> findMyKeyValue(JsonElement element, String key, String searchKey) {

    //OBJECT
    if(element.isJsonObject()) {
        JsonObject jsonObject = element.getAsJsonObject();

        //loop through all elements in object

        for (Map.Entry<String,JsonElement> entry : jsonObject.entrySet()) {
            JsonElement array = entry.getValue();
            findMyKeyValue(array, entry.getKey(), searchKey);

        }

    //ARRAY
    } else if(element.isJsonArray()) {
        //when an array is found keep 'key' as that is the array's name i.e. pass it down

        JsonArray jsonArray = element.getAsJsonArray();

        //loop through all elements in array
        for (JsonElement childElement : jsonArray) {
            findMyKeyValue(childElement, key, searchKey);
        }

    //NEITHER
    } else {

        //System.out.println("SKey: " + searchKey + " Key: " + key );

            if (key.equals(searchKey)){
                listOfValues.add(element.getAsString());
            }
    }
    return listOfValues;
}

Can't use SURF, SIFT in OpenCV

There is a pip source that makes this very easy.

  1. If you have another version of opencv-python installed use this command to remove it to avoid conflicts:

    pip uninstall opencv-python
    
  2. Then install the contrib version with this:

    pip install opencv-contrib-python
    
  3. SIFT usage:

    import cv2
    sift = cv2.xfeatures2d.SIFT_create()
    

how to set radio button checked in edit mode in MVC razor view

You have written like

@Html.RadioButtonFor(model => model.gender, "Male", new { @checked = true }) and
@Html.RadioButtonFor(model => model.gender, "Female", new { @checked = true })

Here you have taken gender as a Enum type and you have written the value for the radio button as a string type- change "Male" to 0 and "Female" to 1.

Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it was created on

Use the following extensions and just pass the action like:

_frmx.PerformSafely(() => _frmx.Show());
_frmx.PerformSafely(() => _frmx.Location = new Point(x,y));

Extension class:

public static class CrossThreadExtensions
{
    public static void PerformSafely(this Control target, Action action)
    {
        if (target.InvokeRequired)
        {
            target.Invoke(action);
        }
        else
        {
            action();
        }
    }

    public static void PerformSafely<T1>(this Control target, Action<T1> action,T1 parameter)
    {
        if (target.InvokeRequired)
        {
            target.Invoke(action, parameter);
        }
        else
        {
            action(parameter);
        }
    }

    public static void PerformSafely<T1,T2>(this Control target, Action<T1,T2> action, T1 p1,T2 p2)
    {
        if (target.InvokeRequired)
        {
            target.Invoke(action, p1,p2);
        }
        else
        {
            action(p1,p2);
        }
    }
}

What is the connection string for localdb for version 11

I installed the mentioned .Net 4.0.2 update but I got the same error message saying:

A network-related or instance-specific error occurred while establishing a connection to SQL Server

I checked the SqlLocalDb via console as follows:

C:\>sqllocaldb create "Test"
LocalDB instance "Test" created with version 11.0.

C:\>sqllocaldb start "Test"
LocalDB instance "Test" started.

C:\>sqllocaldb info "Test"
Name:               Test
Version:            11.0.2100.60
Shared name:
Owner:              PC\TESTUSER
Auto-create:        No
State:              Running
Last start time:    05.09.2012 21:14:14
Instance pipe name: np:\\.\pipe\LOCALDB#B8A5271F\tsql\query

This means that SqlLocalDb is installed and running correctly. So what was the reason that I could not connect to SqlLocalDB via .Net code with this connectionstring: Server=(LocalDB)\v11.0;Integrated Security=true;?

Then I realized that my application was compiled for DotNet framework 3.5 but SqlLocalDb only works for DotNet 4.0.

After correcting this, the problem was solved.

php resize image on upload

If you want to use Imagick out of the box (included with most PHP distributions), it's as easy as...

$image = new Imagick();
$image_filehandle = fopen('some/file.jpg', 'a+');
$image->readImageFile($image_filehandle);

$image->scaleImage(100,200,FALSE);

$image_icon_filehandle = fopen('some/file-icon.jpg', 'a+');
$image->writeImageFile($image_icon_filehandle);

You will probably want to calculate width and height more dynamically based on the original image. You can get an image's current width and height, using the above example, with $image->getImageHeight(); and $image->getImageWidth();

How to configure CORS in a Spring Boot + Spring Security application?

Solution for Webflux (Reactive) Spring Boot, since Google shows this as one of the top results when searching with 'Reactive' for this same problem. Using Spring boot version 2.2.2

@Bean
public SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
  return http.cors().and().build();
}

@Bean
public CorsWebFilter corsFilter() {
  CorsConfiguration config = new CorsConfiguration();

  config.applyPermitDefaultValues();

  config.addAllowedHeader("Authorization");

  UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
  source.registerCorsConfiguration("/**", config);

  return new CorsWebFilter(source);
}

For a full example, with the setup that works with a custom authentication manager (in my case JWT authentication). See here https://gist.github.com/FiredLight/d973968cbd837048987ab2385ba6b38f

IntelliJ shortcut to show a popup of methods in a class that can be searched

You can type "this." and wait a second, a popup with methods and properties will display.

Not a shortcut, but it works for me.

PS: if you are in a static method, type the class name.

How to efficiently check if variable is Array or Object (in NodeJS & V8)?

If its just about detecting whether or not you're dealing with an Object, I could think of

Object.getPrototypeOf( obj ) === Object.prototype

However, this would probably fail for non-object primitive values. Actually there is nothing wrong with invoking .toString() to retreive the [[cclass]] property. You can even create a nice syntax like

var type = Function.prototype.call.bind( Object.prototype.toString );

and then use it like

if( type( obj ) === '[object Object]' ) { }

It might not be the fastest operation but I don't think the performance leak there is too big.

Why use a READ UNCOMMITTED isolation level?

I always use READ UNCOMMITTED now. It's fast with the least issues. When using other isolations you will almost always come across some Blocking issues.

As long as you use Auto Increment fields and pay a little more attention to inserts then your fine, and you can say goodbye to blocking issues.

You can make errors with READ UNCOMMITED but to be honest, it is very easy make sure your inserts are full proof. Inserts/Updates which use the results from a select are only thing you need to watch out for. (Use READ COMMITTED here, or ensure that dirty reads aren't going to cause a problem)

So go the Dirty Reads (Specially for big reports), your software will run smoother...

Google Chrome Printing Page Breaks

I had an issue similar to this but I found the solution eventually. I had overflow-x: hidden; applied to the <html> tag so no matter what I did below in the DOM, it would never allow page breaks. By reverting to overflow-x: visible; it worked fine.

Hopefully this helps somebody out there.

Git/GitHub can't push to master

I added my pubkey to github.com and this was successful:

ssh -T [email protected]

But I received the "You can't push" error after having wrongly done this:

git clone git://github.com/mygithubacct/dotfiles.git
git remote add origin [email protected]:mygithubacct/dotfiles.git
...edit/add/commit
git push origin master

Instead of doing what I should have done:

mkdir dotfiles
cd dotfiles
git init
git remote add origin [email protected]:mygithubacct/dotfiles.git
git pull origin master
...edit/add/commit
git push origin master

How to display raw html code in PRE or something like it but without escaping it

@GitaarLAB and @Jukka elaborate that <xmp> tag is obsolete, but still the best. When I use it like this

<xmp>
<div>Lorem ipsum</div>
<p>Hello</p>
</xmp>

then the first EOL is inserted in the code, and it looks awful.

It can be solved by removing that EOL

<xmp><div>Lorem ipsum</div>
<p>Hello</p>
</xmp>

but then it looks bad in the source. I used to solve it with wrapping <div>, but recently I figured out a nice CSS3 rule, I hope it also helps somebody:

xmp { margin: 5px 0; padding: 0 5px 5px 5px; background: #CCC; }
xmp:before { content: ""; display: block; height: 1em; margin: 0 -5px -2em -5px; }

This looks better.

Difference between a SOAP message and a WSDL?

SOAP : It's an open standard XML based Communication protocol which is used to exchange information from the user to web service or vice versa. The soap is just the document in which the data are organized in some Manner. For every request and response separate soap may be present.

WSDL: In soap the data are organized in some manner and this organization is specified in WSDL, The data type which has to be used are also specified here. For request and response single WSDL will be present

How to remove item from array by value?

What you're after is filter

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

This will allow you to do the following:

var ary = ['three', 'seven', 'eleven'];
var aryWithoutSeven = ary.filter(function(value) { return value != 'seven' });
console.log(aryWithoutSeven); // returns ['three', 'eleven']

This was also noted in this thread somewhere else: https://stackoverflow.com/a/20827100/293492

Convert UTC Epoch to local date

var myDate = new Date( your epoch date *1000);

source - https://www.epochconverter.com/programming/#javascript

Converting JSON String to Dictionary Not List

The best way to Load JSON Data into Dictionary is You can user the inbuilt json loader.

Below is the sample snippet that can be used.

import json
f = open("data.json")
data = json.load(f))
f.close()
type(data)
print(data[<keyFromTheJsonFile>])

What's the best practice for primary keys in tables?

I always use an autonumber or identity field.

I worked for a client who had used SSN as a primary key and then because of HIPAA regulations was forced to change to a "MemberID" and it caused a ton of problems when updating the foreign keys in related tables. Sticking to a consistent standard of an identity column has helped me avoid a similar problem in all of my projects.

How to change the style of a DatePicker in android?

Create a new style

<style name="my_dialog_theme" parent="ThemeOverlay.AppCompat.Dialog">
    <item name="colorAccent">@color/colorAccent</item>                   <!--header background-->
    <item name="android:windowBackground">@color/colorPrimary</item>     <!--calendar background-->
    <item name="android:colorControlActivated">@color/colorAccent</item> <!--selected day-->
    <item name="android:textColorPrimary">@color/colorPrimaryText</item> <!--days of the month-->
    <item name="android:textColorSecondary">@color/colorAccent</item>    <!--days of the week-->
</style>

Then initialize the dialog

Calendar mCalendar = new GregorianCalendar();
mCalendar.setTime(new Date());

new DatePickerDialog(mContext, R.style.my_dialog_theme, new DatePickerDialog.OnDateSetListener() {
    @Override
    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
        //do something with the date
    }
}, mCalendar.get(Calendar.YEAR), mCalendar.get(Calendar.MONTH), mCalendar.get(Calendar.DAY_OF_MONTH)).show();

Result:

enter image description here

MySQL: Quick breakdown of the types of joins

I have 2 tables like this:

> SELECT * FROM table_a;
+------+------+
| id   | name |
+------+------+
|    1 | row1 |
|    2 | row2 |
+------+------+

> SELECT * FROM table_b;
+------+------+------+
| id   | name | aid  |
+------+------+------+
|    3 | row3 |    1 |
|    4 | row4 |    1 |
|    5 | row5 | NULL |
+------+------+------+

INNER JOIN cares about both tables

INNER JOIN cares about both tables, so you only get a row if both tables have one. If there is more than one matching pair, you get multiple rows.

> SELECT * FROM table_a a INNER JOIN table_b b ON a.id=b.aid;
+------+------+------+------+------+
| id   | name | id   | name | aid  |
+------+------+------+------+------+
|    1 | row1 |    3 | row3 | 1    |
|    1 | row1 |    4 | row4 | 1    |
+------+------+------+------+------+

It makes no difference to INNER JOIN if you reverse the order, because it cares about both tables:

> SELECT * FROM table_b b INNER JOIN table_a a ON a.id=b.aid;
+------+------+------+------+------+
| id   | name | aid  | id   | name |
+------+------+------+------+------+
|    3 | row3 | 1    |    1 | row1 |
|    4 | row4 | 1    |    1 | row1 |
+------+------+------+------+------+

You get the same rows, but the columns are in a different order because we mentioned the tables in a different order.

LEFT JOIN only cares about the first table

LEFT JOIN cares about the first table you give it, and doesn't care much about the second, so you always get the rows from the first table, even if there is no corresponding row in the second:

> SELECT * FROM table_a a LEFT JOIN table_b b ON a.id=b.aid;
+------+------+------+------+------+
| id   | name | id   | name | aid  |
+------+------+------+------+------+
|    1 | row1 |    3 | row3 | 1    |
|    1 | row1 |    4 | row4 | 1    |
|    2 | row2 | NULL | NULL | NULL |
+------+------+------+------+------+

Above you can see all rows of table_a even though some of them do not match with anything in table b, but not all rows of table_b - only ones that match something in table_a.

If we reverse the order of the tables, LEFT JOIN behaves differently:

> SELECT * FROM table_b b LEFT JOIN table_a a ON a.id=b.aid;
+------+------+------+------+------+
| id   | name | aid  | id   | name |
+------+------+------+------+------+
|    3 | row3 | 1    |    1 | row1 |
|    4 | row4 | 1    |    1 | row1 |
|    5 | row5 | NULL | NULL | NULL |
+------+------+------+------+------+

Now we get all rows of table_b, but only matching rows of table_a.

RIGHT JOIN only cares about the second table

a RIGHT JOIN b gets you exactly the same rows as b LEFT JOIN a. The only difference is the default order of the columns.

> SELECT * FROM table_a a RIGHT JOIN table_b b ON a.id=b.aid;
+------+------+------+------+------+
| id   | name | id   | name | aid  |
+------+------+------+------+------+
|    1 | row1 |    3 | row3 | 1    |
|    1 | row1 |    4 | row4 | 1    |
| NULL | NULL |    5 | row5 | NULL |
+------+------+------+------+------+

This is the same rows as table_b LEFT JOIN table_a, which we saw in the LEFT JOIN section.

Similarly:

> SELECT * FROM table_b b RIGHT JOIN table_a a ON a.id=b.aid;
+------+------+------+------+------+
| id   | name | aid  | id   | name |
+------+------+------+------+------+
|    3 | row3 | 1    |    1 | row1 |
|    4 | row4 | 1    |    1 | row1 |
| NULL | NULL | NULL |    2 | row2 |
+------+------+------+------+------+

Is the same rows as table_a LEFT JOIN table_b.

No join at all gives you copies of everything

If you write your tables with no JOIN clause at all, just separated by commas, you get every row of the first table written next to every row of the second table, in every possible combination:

> SELECT * FROM table_b b, table_a;
+------+------+------+------+------+
| id   | name | aid  | id   | name |
+------+------+------+------+------+
|    3 | row3 | 1    |    1 | row1 |
|    3 | row3 | 1    |    2 | row2 |
|    4 | row4 | 1    |    1 | row1 |
|    4 | row4 | 1    |    2 | row2 |
|    5 | row5 | NULL |    1 | row1 |
|    5 | row5 | NULL |    2 | row2 |
+------+------+------+------+------+

(This is from my blog post Examples of SQL join types)

How can I add 1 day to current date?

To add one day to a date object:

var date = new Date();

// add a day
date.setDate(date.getDate() + 1);

Using SSH keys inside docker container

'you can selectively let remote servers access your local ssh-agent as if it was running on the server'

https://developer.github.com/guides/using-ssh-agent-forwarding/

Composer require runs out of memory. PHP Fatal error: Allowed memory size of 1610612736 bytes exhausted

Another solution from the manual:

Composer also respects a memory limit defined by the COMPOSER_MEMORY_LIMIT environment variable:

COMPOSER_MEMORY_LIMIT=-1 composer.phar <...>

Or in my case

export COMPOSER_MEMORY_LIMIT=-1
composer <...>

SQL Server - transactions roll back on error?

If one of the inserts fail, or any part of the command fails, does SQL server roll back the transaction?

No, it does not.

If it does not rollback, do I have to send a second command to roll it back?

Sure, you should issue ROLLBACK instead of COMMIT.

If you want to decide whether to commit or rollback the transaction, you should remove the COMMIT sentence out of the statement, check the results of the inserts and then issue either COMMIT or ROLLBACK depending on the results of the check.

Select info from table where row has max date

You can use a window MAX() like this:

SELECT
  *, 
  max_date = MAX(date) OVER (PARTITION BY group)
FROM table

to get max dates per group alongside other data:

group  date      cash  checks  max_date
-----  --------  ----  ------  --------
1      1/1/2013  0     0       1/3/2013
2      1/1/2013  0     800     1/1/2013
1      1/3/2013  0     700     1/3/2013
3      1/1/2013  0     600     1/5/2013
1      1/2/2013  0     400     1/3/2013
3      1/5/2013  0     200     1/5/2013

Using the above output as a derived table, you can then get only rows where date matches max_date:

SELECT
  group,
  date,
  checks
FROM (
  SELECT
    *, 
    max_date = MAX(date) OVER (PARTITION BY group)
  FROM table
) AS s
WHERE date = max_date
;

to get the desired result.

Basically, this is similar to @Twelfth's suggestion but avoids a join and may thus be more efficient.

You can try the method at SQL Fiddle.

How to generate a range of numbers between two numbers?

I recently wrote this inline table valued function to solve this very problem. It's not limited in range other than memory and storage. It accesses no tables so there's no need for disk reads or writes generally. It adds joins values exponentially on each iteration so it's very fast even for very large ranges. It creates ten million records in five seconds on my server. It also works with negative values.

CREATE FUNCTION [dbo].[fn_ConsecutiveNumbers]
(   
    @start int,
    @end  int
) RETURNS TABLE 
RETURN 

select
    x268435456.X
    | x16777216.X
    | x1048576.X
    | x65536.X
    | x4096.X
    | x256.X
    | x16.X
    | x1.X
    + @start
     X
from
(VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13),(14),(15)) as x1(X)
join
(VALUES (0),(16),(32),(48),(64),(80),(96),(112),(128),(144),(160),(176),(192),(208),(224),(240)) as x16(X)
on x1.X <= @end-@start and x16.X <= @end-@start
join
(VALUES (0),(256),(512),(768),(1024),(1280),(1536),(1792),(2048),(2304),(2560),(2816),(3072),(3328),(3584),(3840)) as x256(X)
on x256.X <= @end-@start
join
(VALUES (0),(4096),(8192),(12288),(16384),(20480),(24576),(28672),(32768),(36864),(40960),(45056),(49152),(53248),(57344),(61440)) as x4096(X)
on x4096.X <= @end-@start
join
(VALUES (0),(65536),(131072),(196608),(262144),(327680),(393216),(458752),(524288),(589824),(655360),(720896),(786432),(851968),(917504),(983040)) as x65536(X)
on x65536.X <= @end-@start
join
(VALUES (0),(1048576),(2097152),(3145728),(4194304),(5242880),(6291456),(7340032),(8388608),(9437184),(10485760),(11534336),(12582912),(13631488),(14680064),(15728640)) as x1048576(X)
on x1048576.X <= @end-@start
join
(VALUES (0),(16777216),(33554432),(50331648),(67108864),(83886080),(100663296),(117440512),(134217728),(150994944),(167772160),(184549376),(201326592),(218103808),(234881024),(251658240)) as x16777216(X)
on x16777216.X <= @end-@start
join
(VALUES (0),(268435456),(536870912),(805306368),(1073741824),(1342177280),(1610612736),(1879048192)) as x268435456(X)
on x268435456.X <= @end-@start
WHERE @end >=
    x268435456.X
    | isnull(x16777216.X, 0)
    | isnull(x1048576.X, 0)
    | isnull(x65536.X, 0)
    | isnull(x4096.X, 0)
    | isnull(x256.X, 0)
    | isnull(x16.X, 0)
    | isnull(x1.X, 0)
    + @start

GO

SELECT X FROM fn_ConsecutiveNumbers(5, 500);

It's handy for date and time ranges as well:

SELECT DATEADD(day,X, 0) DayX 
FROM fn_ConsecutiveNumbers(datediff(day,0,'5/8/2015'), datediff(day,0,'5/31/2015'))

SELECT DATEADD(hour,X, 0) HourX 
FROM fn_ConsecutiveNumbers(datediff(hour,0,'5/8/2015'), datediff(hour,0,'5/8/2015 12:00 PM'));

You could use a cross apply join on it to split records based on values in the table. So for example to create a record for every minute on a time range in a table you could do something like:

select TimeRanges.StartTime,
    TimeRanges.EndTime,
    DATEADD(minute,X, 0) MinuteX
FROM TimeRanges
cross apply fn_ConsecutiveNumbers(datediff(hour,0,TimeRanges.StartTime), 
        datediff(hour,0,TimeRanges.EndTime)) ConsecutiveNumbers

Datetime format Issue: String was not recognized as a valid DateTime

change the culture and try out like this might work for you

string[] formats= { "MM/dd/yyyy HH:mm" }
var dateTime = DateTime.ParseExact("04/30/2013 23:00", 
     formats, new CultureInfo("en-US"), DateTimeStyles.None);

Check for details : DateTime.ParseExact Method (String, String[], IFormatProvider, DateTimeStyles)

How to change Format of a Cell to Text using VBA

for large numbers that display with scientific notation set format to just '#'

LINQ order by null column where order is ascending and nulls should be last

Try putting both columns in the same orderby.

orderby p.LowestPrice.HasValue descending, p.LowestPrice

Otherwise each orderby is a separate operation on the collection re-ordering it each time.

This should order the ones with a value first, "then" the order of the value.

Want to move a particular div to right

This will do the job:

_x000D_
_x000D_
<div style="position:absolute; right:0;">Hello world</div>
_x000D_
_x000D_
_x000D_

Exit from app when click button in android phonegap?

sorry i can't reply in comment. just FYI, these codes

if (navigator.app) {
navigator.app.exitApp();
}
else if (navigator.device) {
  navigator.device.exitApp();
}
else {
          window.close();
}

i confirm doesn't work. i use phonegap 6.0.5 and cordova 6.2.0

C - casting int to char and append char to char

int myInt = 65;

char myChar = (char)myInt;  // myChar should now be the letter A

char[20] myString = {0}; // make an empty string.

myString[0] = myChar;
myString[1] = myChar; // Now myString is "AA"

This should all be found in any intro to C book, or by some basic online searching.

HTTP Get with 204 No Content: Is that normal

I use GET/204 with a RESTful collection that is a positional array of known fixed length but with holes.

GET /items
    200: ["a", "b", null]

GET /items/0
    200: "a"

GET /items/1
    200: "b"

GET /items/2
    204:

GET /items/3
    404: Not Found

MessageBox with YesNoCancel - No & Cancel triggers same event

Use:

Dim n As String = MsgBox("Do you really want to exit?", MsgBoxStyle.YesNo, "Confirmation Dialog Box")
If n = vbYes Then
    MsgBox("Current Form is closed....")
    Me.Close() 'Current Form Closed
    Yogi_Cottex.Show() 'Form Name.show()
End If

How do I get multiple subplots in matplotlib?

read the documentation: matplotlib.pyplot.subplots

pyplot.subplots() returns a tuple fig, ax which is unpacked in two variables using the notation

fig, axes = plt.subplots(nrows=2, ncols=2)

the code

fig = plt.figure()
axes = fig.subplots(nrows=2, ncols=2)

does not work because subplots()is a function in pyplot not a member of the object Figure.

password for postgres

Set the default password in the .pgpass file. If the server does not save the password, it is because it is not set in the .pgpass file, or the permissions are open and the file is therefore ignored.

Read more about the password file here.

Also, be sure to check the permissions: on *nix systems the permissions on .pgpass must disallow any access to world or group; achieve this by the command chmod 0600 ~/.pgpass. If the permissions are less strict than this, the file will be ignored.

Have you tried logging-in using PGAdmin? You can save the password there, and modify the pgpass file.

Check if Internet Connection Exists with jQuery?

A much simpler solution:

<script language="javascript" src="http://maps.google.com/maps/api/js?v=3.2&sensor=false"></script>

and later in the code:

var online;
// check whether this function works (online only)
try {
  var x = google.maps.MapTypeId.TERRAIN;
  online = true;
} catch (e) {
  online = false;
}
console.log(online);

When not online the google script will not be loaded thus resulting in an error where an exception will be thrown.

How to determine if .NET Core is installed

After all the other answers, this might prove useful.

Open your application in Visual Studio. In Solutions Explorer, right click your project. Click Properties. Click Application. Under "Target Framework" click the dropdown button and there you are, all of the installed frameworks.

BTW - you may now choose which framework you want.

How can I disable editing cells in a WPF Datagrid?

The DataGrid has an XAML property IsReadOnly that you can set to true:

<my:DataGrid
    IsReadOnly="True"
/>

cannot import name patterns

Yes:

from django.conf.urls.defaults import ... # is for django 1.3
from django.conf.urls  import ...         # is for django 1.4

I met this problem too.

Serializing class instance to JSON

I believe instead of inheritance as suggested in accepted answer, it's better to use polymorphism. Otherwise you have to have a big if else statement to customize encoding of every object. That means create a generic default encoder for JSON as:

def jsonDefEncoder(obj):
   if hasattr(obj, 'jsonEnc'):
      return obj.jsonEnc()
   else: #some default behavior
      return obj.__dict__

and then have a jsonEnc() function in each class you want to serialize. e.g.

class A(object):
   def __init__(self,lengthInFeet):
      self.lengthInFeet=lengthInFeet
   def jsonEnc(self):
      return {'lengthInMeters': lengthInFeet * 0.3 } # each foot is 0.3 meter

Then you call json.dumps(classInstance,default=jsonDefEncoder)

Javascript split regex question

you could just use

date.split(/-/);

or

date.split('-');

percentage of two int?

float percent = (n / (v * 1.0f)) *100

How to convert upper case letters to lower case

To convert a string to lower case in Python, use something like this.

list.append(sentence.lower())

I found this in the first result after searching for "python upper to lower case".

C#, Looping through dataset and show each record from a dataset column

DateTime TaskStart = DateTime.Parse(dr["TaskStart"].ToString());

Difference between Ctrl+Shift+F and Ctrl+I in Eclipse

If you press CTRL + I it will just format tabs/whitespaces in code and pressing CTRL + SHIFT + F format all code that is format tabs/whitespaces and also divide code lines in a way that it is visible without horizontal scroll.

PHP preg_replace special characters

$newstr = preg_replace('/[^a-zA-Z0-9\']/', '_', "There wouldn't be any");
$newstr = str_replace("'", '', $newstr);

I put them on two separate lines to make the code a little more clear.

Note: If you're looking for Unicode support, see Filip's answer below. It will match all characters that register as letters in addition to A-z.

Python one-line "for" expression

for item in array: array2.append (item)

Or, in this case:

array2 += array

Set Response Status Code

I had the same issue with CakePHP 2.0.1

I tried using

header( 'HTTP/1.1 400 BAD REQUEST' );

and

$this->header( 'HTTP/1.1 400 BAD REQUEST' );

However, neither of these solved my issue.

I did eventually resolve it by using

$this->header( 'HTTP/1.1 400: BAD REQUEST' );

After that, no errors or warning from php / CakePHP.

*edit: In the last $this->header function call, I put a colon (:) between the 400 and the description text of the error.

Javascript - User input through HTML input tag to set a Javascript variable?

When your script is running, it blocks the page from doing anything. You can work around this with one of two ways:

  • Use var foo = prompt("Give me input");, which will give you the string that the user enters into a popup box (or null if they cancel it)
  • Split your code into two function - run one function to set up the user interface, then provide the second function as a callback that gets run when the user clicks the button.

Proxies with Python 'Requests' module

You can refer to the proxy documentation here.

If you need to use a proxy, you can configure individual requests with the proxies argument to any request method:

import requests

proxies = {
  "http": "http://10.10.1.10:3128",
  "https": "https://10.10.1.10:1080",
}

requests.get("http://example.org", proxies=proxies)

To use HTTP Basic Auth with your proxy, use the http://user:[email protected]/ syntax:

proxies = {
    "http": "http://user:[email protected]:3128/"
}

How do I set a JLabel's background color?

The JLabel background is transparent by default. Set the opacity at true like that:

label.setOpaque(true);

how to use javascript Object.defineProperty

Since you asked a similar question, let's take it to step by step. It's a bit longer, but it may save you much more time than I have spent on writing this:

Property is an OOP feature designed for clean separation of client code. For example, in some e-shop you might have objects like this:

function Product(name,price) {
  this.name = name;
  this.price = price;
  this.discount = 0;
}

var sneakers = new Product("Sneakers",20); // {name:"Sneakers",price:20,discount:0}
var tshirt = new Product("T-shirt",10);  // {name:"T-shirt",price:10,discount:0}

Then in your client code (the e-shop), you can add discounts to your products:

function badProduct(obj) { obj.discount+= 20; ... }
function generalDiscount(obj) { obj.discount+= 10; ... }
function distributorDiscount(obj) { obj.discount+= 15; ... }

Later, the e-shop owner might realize that the discount can't be greater than say 80%. Now you need to find EVERY occurrence of the discount modification in the client code and add a line

if(obj.discount>80) obj.discount = 80;

Then the e-shop owner may further change his strategy, like "if the customer is reseller, the maximal discount can be 90%". And you need to do the change on multiple places again plus you need to remember to alter these lines anytime the strategy is changed. This is a bad design. That's why encapsulation is the basic principle of OOP. If the constructor was like this:

function Product(name,price) {
  var _name=name, _price=price, _discount=0;
  this.getName = function() { return _name; }
  this.setName = function(value) { _name = value; }
  this.getPrice = function() { return _price; }
  this.setPrice = function(value) { _price = value; }
  this.getDiscount = function() { return _discount; }
  this.setDiscount = function(value) { _discount = value; } 
}

Then you can just alter the getDiscount (accessor) and setDiscount (mutator) methods. The problem is that most of the members behave like common variables, just the discount needs special care here. But good design requires encapsulation of every data member to keep the code extensible. So you need to add lots of code that does nothing. This is also a bad design, a boilerplate antipattern. Sometimes you can't just refactor the fields to methods later (the eshop code may grow large or some third-party code may depend on the old version), so the boilerplate is lesser evil here. But still, it is evil. That's why properties were introduced into many languages. You could keep the original code, just transform the discount member into a property with get and set blocks:

function Product(name,price) {
  this.name = name;
  this.price = price;
//this.discount = 0; // <- remove this line and refactor with the code below
  var _discount; // private member
  Object.defineProperty(this,"discount",{
    get: function() { return _discount; },
    set: function(value) { _discount = value; if(_discount>80) _discount = 80; }
  });
}

// the client code
var sneakers = new Product("Sneakers",20);
sneakers.discount = 50; // 50, setter is called
sneakers.discount+= 20; // 70, setter is called
sneakers.discount+= 20; // 80, not 90!
alert(sneakers.discount); // getter is called

Note the last but one line: the responsibility for correct discount value was moved from the client code (e-shop definition) to the product definition. The product is responsible for keeping its data members consistent. Good design is (roughly said) if the code works the same way as our thoughts.

So much about properties. But javascript is different from pure Object-oriented languages like C# and codes the features differently:

In C#, transforming fields into properties is a breaking change, so public fields should be coded as Auto-Implemented Properties if your code might be used in the separately compiled client.

In Javascript, the standard properties (data member with getter and setter described above) are defined by accessor descriptor (in the link you have in your question). Exclusively, you can use data descriptor (so you can't use i.e. value and set on the same property):

  • accessor descriptor = get + set (see the example above)
    • get must be a function; its return value is used in reading the property; if not specified, the default is undefined, which behaves like a function that returns undefined
    • set must be a function; its parameter is filled with RHS in assigning a value to property; if not specified, the default is undefined, which behaves like an empty function
  • data descriptor = value + writable (see the example below)
    • value default undefined; if writable, configurable and enumerable (see below) are true, the property behaves like an ordinary data field
    • writable - default false; if not true, the property is read only; attempt to write is ignored without error*!

Both descriptors can have these members:

  • configurable - default false; if not true, the property can't be deleted; attempt to delete is ignored without error*!
  • enumerable - default false; if true, it will be iterated in for(var i in theObject); if false, it will not be iterated, but it is still accessible as public

* unless in strict mode - in that case JS stops execution with TypeError unless it is caught in try-catch block

To read these settings, use Object.getOwnPropertyDescriptor().

Learn by example:

var o = {};
Object.defineProperty(o,"test",{
  value: "a",
  configurable: true
});
console.log(Object.getOwnPropertyDescriptor(o,"test")); // check the settings    

for(var i in o) console.log(o[i]); // nothing, o.test is not enumerable
console.log(o.test); // "a"
o.test = "b"; // o.test is still "a", (is not writable, no error)
delete(o.test); // bye bye, o.test (was configurable)
o.test = "b"; // o.test is "b"
for(var i in o) console.log(o[i]); // "b", default fields are enumerable

If you don't wish to allow the client code such cheats, you can restrict the object by three levels of confinement:

  • Object.preventExtensions(yourObject) prevents new properties to be added to yourObject. Use Object.isExtensible(<yourObject>) to check if the method was used on the object. The prevention is shallow (read below).
  • Object.seal(yourObject) same as above and properties can not be removed (effectively sets configurable: false to all properties). Use Object.isSealed(<yourObject>) to detect this feature on the object. The seal is shallow (read below).
  • Object.freeze(yourObject) same as above and properties can not be changed (effectively sets writable: false to all properties with data descriptor). Setter's writable property is not affected (since it doesn't have one). The freeze is shallow: it means that if the property is Object, its properties ARE NOT frozen (if you wish to, you should perform something like "deep freeze", similar to deep copy - cloning). Use Object.isFrozen(<yourObject>) to detect it.

You don't need to bother with this if you write just a few lines fun. But if you want to code a game (as you mentioned in the linked question), you should care about good design. Try to google something about antipatterns and code smell. It will help you to avoid situations like "Oh, I need to completely rewrite my code again!", it can save you months of despair if you want to code a lot. Good luck.

Configure hibernate to connect to database via JNDI Datasource

Inside applicationContext.xml file of a maven Hibernet web app project below settings worked for me.

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/jee 
        http://www.springframework.org/schema/jee/spring-jee-3.0.xsd">



  <jee:jndi-lookup id="dataSource"
                 jndi-name="Give_DataSource_Path_From_Your_Server"
                 expected-type="javax.sql.DataSource" />


Hope It will help someone.Thanks!

Use async await with Array.map

There's another solution for it if you are not using native Promises but Bluebird.

You could also try using Promise.map(), mixing the array.map and Promise.all

In you case:

  var arr = [1,2,3,4,5];

  var results: number[] = await Promise.map(arr, async (item): Promise<number> => {
    await callAsynchronousOperation(item);
    return item + 1;
  });

How to exit from the application and show the home screen?

If you want to exit from your application. Then use this code inside your button pressed event. like:

public void onBackPressed()
{
    moveTaskToBack(true);
    android.os.Process.killProcess(android.os.Process.myPid());
    System.exit(1);
}

Docker: Copying files from Docker container to host

If you don't have a running container, just an image, and assuming you want to copy just a text file, you could do something like this:

docker run the-image cat path/to/container/file.txt > path/to/host/file.txt

How to submit form on change of dropdown list?

To those in the answer above. It's definitely JavaScript. It's just inline.

BTW the jQuery equivalent if you want to apply to all selects:

$('form select').on('change', function(){
    $(this).closest('form').submit();
});

Issue pushing new code in Github

Considering if you haven't committed your changes in a while, maybe doing this will work for you.

git add files
git commit -m "Your Commit"
git push -u origin master

That worked for me, hopefully it does for you too.

Send JSON data via POST (ajax) and receive json response from Controller (MVC)

Create a model

public class Person
{
    public string Name { get; set; }
    public string Address { get; set; }
    public string Phone { get; set; }
}

Controllers Like Below

    public ActionResult PersonTest()
    {
        return View();
    }

    [HttpPost]
    public ActionResult PersonSubmit(Vh.Web.Models.Person person)
    {
        System.Threading.Thread.Sleep(2000);  /*simulating slow connection*/

        /*Do something with object person*/


        return Json(new {msg="Successfully added "+person.Name });
    }

Javascript

<script type="text/javascript">
    function send() {
        var person = {
            name: $("#id-name").val(),
            address:$("#id-address").val(),
            phone:$("#id-phone").val()
        }

        $('#target').html('sending..');

        $.ajax({
            url: '/test/PersonSubmit',
            type: 'post',
            dataType: 'json',
            contentType: 'application/json',
            success: function (data) {
                $('#target').html(data.msg);
            },
            data: JSON.stringify(person)
        });
    }
</script>

Does SVG support embedding of bitmap images?

It is also possible to include bitmaps. I think you also can use transformations on that.

Connect to external server by using phpMyAdmin

in the config.inc.php, remove all lines with "$cfg['Servers']" , and keep ONLY the "$cfg['Servers'][$i]['host']"

Using PHP variables inside HTML tags?

HI Jasper,

you can do this:

<?
sprintf("<a href=\"http://www.whatever.com/%s\">Click Here</a>", $param);
?>

Trigger an event on `click` and `enter`

$('#form').keydown(function(e){
    if (e.keyCode === 13) { // If Enter key pressed
        $(this).trigger('submit');
    }
});

What is the best way to trigger onchange event in react js

If you are using Backbone and React, I'd recommend one of the following,

They both help integrate Backbone models and collections with React views. You can use Backbone events just like you do with Backbone views. I've dabbled in both and didn't see much of a difference except one is a mixin and the other changes React.createClass to React.createBackboneClass.

correct quoting for cmd.exe for multiple arguments

Spaces are used for separating Arguments. In your case C:\Program becomes argument. If your file path contains spaces then add Double quotation marks. Then cmd will recognize it as single argument.

How can I disable notices and warnings in PHP within the .htaccess file?

Use:

ini_set('display_errors','off');

It is working fine in WordPress' config.php.

Last executed queries for a specific database

This works for me to find queries on any database in the instance. I'm sysadmin on the instance (check your privileges):

SELECT deqs.last_execution_time AS [Time], dest.text AS [Query], dest.*
FROM sys.dm_exec_query_stats AS deqs
CROSS APPLY sys.dm_exec_sql_text(deqs.sql_handle) AS dest
WHERE dest.dbid = DB_ID('msdb')
ORDER BY deqs.last_execution_time DESC

This is the same answer that Aaron Bertrand provided but it wasn't placed in an answer.